The half-blood son of Natalie Chase and the Norse god Frey, and our hero.
- Ambiguously Bi: He has a certain amount of Ship Tease with Alex regardless of what gender he/she is. He also appreciates beauty in the men and women he encounters. Stops being ambiguous in the third book, when he shares a kiss with Alex during a particular moment when the latter is identifying as male. Magnus' narration even comments on being surprised with how okay he is with it.
- Audience Surrogate: He's only vaguely familiar with Norse mythology (not that a kid living on the streets would have very much access or interest in seeking out such knowledge), providing ample opportunities to explain it outside of well-known figures like Thor and Loki.
- Berserk Button: Stealing his falafel seems to be foolish.
- Bookworm: He loves to read and makes not a few Shout Outs to classical literature in stark contrast with Percy.
- Celebrity Resemblance: It's stated more than once that he looks like a young Kurt Cobain.
- Combo Platter Powers: Being a son of Frey comes with quite a few interesting abilities. Aside from his Healing Hands and Alf Seidr, Magnus has shown immunity to extreme hot and cold temperatures to the point that he's completely unfazed by the overwhelming heat of Muspelheim. He has a limited form of Weather Manipulation, being able to turn an area around him warm and sunny, and he can keep ships he's riding on from capsizing or flipping over, which Samirah theorizes is an ability he inherited from his grandfather, Njord.
- Contrasting Sequel Main Character/Foil: In oh so many ways to Percy. He's a blond, practically clueless in a fight, died early in his adventure (he comes back, but still), likes reading, and doesn't have any particular attention deficit problems. He's also much better at talking out his problems than Percy, who by contrast lets Annabeth handle most of the thinking. Percy took to demigod life like a duck to water, Magnus wants nothing but to get out of einherji life. He also hates the color blue, which by contrast is Percy's favorite color.
- Also, he's more of a Guile Hero than Percy, since his father Frey, god of summer, fertility, and growth was never much of a fighter himself, so he lacks the natural talent or overwhelming power Percy, whose father is the god of storms and the ocean, has.
- There's also a lot of contrast in their initial relationships with their fathers. Unlike Percy, Magnus has never resented his father or even really wondered about who he is, and when they finally meet, he embraces him and is accepting. Percy, on the other hand, felt understandably awkward and distant from Poseidon, neither really knowing how to feel about each other until more time had passed.
- Cruel and Unusual Death:
- His initial death before becoming an einherjar comes when Surt chucks a hunk of molten rock through his stomach, which gets lodged there and proceeds to burn him from the inside out.
- In The Hammer of Thor, Loki uses his powers to establish a blood connection between Randolph and Magnus, which allows him to channel his divine power into the latter, cooking him alive and nearly causing him to go nuclear before Alex beheads him to put a stop to it. Thankfully, this takes place on the training field of Valhalla, so he comes back.
- Also in Valhalla, and Played for Laughs, Magnus mentions suffocation to death by mint chocolate as one of his least favorite ways to die.
- Dangerous 16th Birthday: Turning sixteen means he's come of age and can claim the Sword of Summer, at which point a lot of people suddenly want to kill or manipulate him.
- Deadpan Snarker: Even moreso than Percy.
- The Cynic: His snark is a bit more acrid than Percy's. Then again, given what he's been through and being homeless for two years, perhaps he has some reason to be a little sour.
- Death Is a Slap on the Wrist: His first death led to a physical upgrade as an einherjar, and while in Valhalla he can't be permanently killed.
- Did You Just Flip Off Cthulhu?: He did indeed, literally; in his first confrontation with the king of the fire giants, Surt, no less.
- Disproportionate Retribution: He considered attacking Utgard-Loki with his sword an appropriate response to the giant eating all his falafel.
- Don't You Dare Pity Me!: Played with. One of the first things he tells the reader is to save their pity over his homeless status (before he became an einherjar). However, he feels this way because most express this pity and then do nothing to help.
- Everyone Can See It: Some people tease Magnus for his crush on Alex, like Halfborn when he says there nothing to be ashamed about liking an argr. To Sam telling him he should talk to Alex especially after Alex kisses Magnus for the first time.
- Flat-Earth Atheist: By his own admission, he doesn't really believe in any sort of higher power, even after becoming an einherjar (in other words, he acknowledges the obvious existence of gods, but not capital-g God).
- He even lampshades it in Book 3, noting that his knowledge of the existence separate pantheons makes him doubt even more that there is any sort of "greater plan".
- Gray Eyes: Just like his cousin, Annabeth.
- Hair of Gold, Heart of Gold: His parentage has given him golden blond hair like his cousin and while he can be a bit of a sourpuss he's very much a great guy to be around.
- Handicapped Badass: He has asthma. It isn't brought up much since he got a Heroic Build though, leading him to speculate that it was cured upon becoming an einherjar.
- Healing Factor: A power he inherited from his father. For reference, he took a spear to the chest, and it only annoyed him. Of course he only figured it out after becoming a einherjar. Since he never tested it while being alive.
- Healing Hands: He later finds that he's able to use his power on others, at the cost of tiring him out considerably (which can be deadly in a fight).
- Heart Is an Awesome Power: As a son of Frey, he can naturally use Alf Seidr (elf magic), which is primarily used for healing, growing, and stopping violence and had been lost for thousands of years. It sounds lame when compared to rune magic until Magnus uses it to disarm an entire group of fire giants, including Surt himself, effectively bringing a huge battle to a halt in one move.
- This also becomes his greatest weapon with his flyting against Loki, where instead of insults, he talks about the great things his friends have done and how he's never alone.
- Heroes Prefer Swords: Is the rightful heir to the Sword of Summer, albeit subverted by the fact that he has no idea how to wield it, leaving Jack to do most of the heavy lifting.
- Heroic Build: Becoming an einherjar gave him an athletic build he never had back when he was human and seemed to cure his asthma.
- I Am Who?: He isn't particularly enthused by Randolph's attempts to quickly explain his divine parentage.
- I Choose to Stay: Odin offers to send Magnus back home permanently as a reward for his quest, but Magnus decides to make Valhalla is home as an einherjar. That said, Odin decides to go ahead and give Magnus and his friends the freedom to visit the Nine Worlds as they choose, which provides ample time to let Magnus visit Annabeth.
- If It's You, It's Okay:The first time Alex kisses him as a guy, he admits that part of him is wondering how he feels being kissed by a dude... and the rest of him is telling himself that since its Alex, its great.
- Indy Ploy: Pulls a lot of these throughout the story (such as the time where he flipped a giant steak knife by jumping on the blade to stab a giantess) and his ability to quickly improvise and think up plans compensates for his lack of combat instinct (much like his cousin).
- Insult of Endearment: Annabeth sometimes playfully refers to him as "Butt", just like when they were kids.
- Like Brother and Sister: With Samirah. In the Hammer of Thor, he says she and Annabeth are the closest thing he has to sisters.
- Knight In Sour Armor: He's snarky, a bit of a smartass, is very angsty on the inside, and would like nothing more but to escape his accursed destiny as the son of Frey, doomed to die at Ragnarok. That said, he ultimately means well, is a good listener, and is the moral center of the group.
- Muscle Angst: A really strange example. In the aptly named chapter "I Never Asked For Biceps" he noticed his einherjar upgrade for the first time in the shower. While this would make most emaciated street kids giddy, he instead interprets it as a reminder of the mess he's been shanghaied into and ends up punching a hole in the wall with his new strength in frustration.
- Muscles Are Meaningful: His einherjar upgrade gave him enough strength to drag a Jotunn sized bull head all the way to beach and onto a boat. He also tore a lamppost out of the ground and used it as a baseball bat.
- Nature Lover: A trait he gets from his mother and father.
- Non-Action Guy: Magnus isn't a natural fighter like previous protagonists. When he fights, it's usually Jack doing the work. Justified, considering the fact that Frey is not a war god like Horus or a total powerhouse like Poseidon. He's learning as he goes without any practice or the battle instinct that Percy has.
- Official Couple: Subverted, while the third book ends with him and Alex having a mutual attraction and acting on it, it's made a point that Alex is a constantly changing person, so there's nothing officially established.
- Open Mouth, Insert Foot: After reeling in Jormungand, he panickedly lets the gargantuan monster know that he wasn't really trying to catch him, he's just using him as bait to draw out Ran. Magnus immediately realizes just how bad that sounds and Jormungand responds as badly as one would expect.
- Power-Strain Blackout: Tends to happen to him when overuses Jack's ability to act independently. He also blacks out at the climax of The Sword Of Summer when he uses his Healing Hands to save Halfborn's life.
- Reality Ensues: After retrieving the Sword of Summer from the bottom of the sea, he valiantly stands up to Surt... and then promptly gets killed because he's the son of a Vanir who has just learned he's a demigod trying to go up against the king of the fire giants.
- Resurrective Immortality: Within Valhalla, Magnus will simply wake up a few hours after any death he suffers. In the other realms, it's Helheim or worse.
- Same Content, Different Rating: Magnus is an inverted, main-character version of this. He stars in a book with same rating as the other main character(s) (if you count Jason), but he's much darker and prone to curse words. And I don't mean curse words.
- Seen It All: Not quite, but living on the streets for two years gave him a hefty dose of weirdness. This makes the shift to supernatural weirdness relatively easy on him. After experiencing the Norse Afterlife, he is even more like this and is confident enough to bet that his life is weirder than his cousin Annabeth's. He loses the bet.
- Sensing You Are Outmatched: When Loki breaks free from his prison, the giant suggests that Magnus and his friends should all attack him together and take advantage of his weakened state. Magnus instinctively knows that they would fail as he can tell that Loki is still much more powerful than all of them put together.
- Ship Tease: With Alex
- Shirtless Scene: When he's checking out his new Einherjar enhanced body during his first night in Valhalla. He then answers a knock at his door, having forgotten to put his shirt or pants back on, much to the embarrassment of both himself and Gunilla.
- A scene like this plays out towards the end of Ship of the Dead, after he returns to Hotel Valhala and Alex comes in with him shirtless which leads to him kissing Magnus.
- The Southpaw: Magnus is left handed. This gives him a bit of trouble when he tries to figure out the proper way to wear his hotel-issued sword.
- Speaks Fluent Animal: Gains the ability to understand animals After tasting the blood of Hearths dads heart. Mallory theorizes that it enhanced the abilities he inherited from his dad, one of most powerful nature gods.
- Trademark Favorite Food: Magnus really, really likes falafel.
- The Watson: Like the other protagonists, he's the one to whom stuff is usually explained.
- Why Did It Have to Be Snakes?: He hates wolves, and it doesn't help that his life as an einherjar has him facing them fairly often.
Thomas Jefferson Jr. (T.J.)
- Bayonet Ya: His weapon of choice is the musket he died with, but he rarely fires it since his opponents are mostly Immune to Bullets. The bone steel bayonet sees a lot more use.
- Beware the Nice Ones: He's by far the most cheerful, optimistic, and upbeat of his hallmates, as well as being a genuinely kind person. He's also an Einherjar with the associated Super Soldier powers and 150 years of combat experience. And as we learn in the third book, he wasn't always this way.
- Berserk Button: Slavery, and hurting slaves. No matter the race, human or giant. It took him a little while to forgive Mallory for killing a number of giant thralls and he was definitely incensed when he first learned about it.
- Black Best Friend: It's never actually mentioned, but he's the son of a freed slave and served in the 54th Massachusetts, which was composed of black soldiers. He's also the first einherji who attempts to befriend Magnus.
- Blessed with Suck: As a son of Tyr, he can't turn down a challenge. This also causes him some problems in "Ship of the Dead".
- Child Soldier: He looks about Magnus' Age (16) but served as a private in the assault on Fort Wagner in the American Civil War. Truth in Television of course due to the nature of the war.
- Dark and Troubled Past: His need to accept challenges led to his own death and the death of his friends. When he arrived at Valhalla, he found out the man who killed him had also become an einherjar, and spent the next fifty years killing him at every opportunity before realizing that the revenge he wanted was poisoning him. The reason he's so kind and optimistic now is that he used to be lost in rage and hate and grew past it.
- Half-Human Hybrid: Son of Tyr, god of bravery.
- The Heart: Of the team, which Magnus points out in the third book.
- Leeroy Jenkins: If taking a hill is involved, he'll throw caution to the wind and charge. It's an American Civil War thing.
- Due to being the son of the god of challenges, hell automatically accept any challenge hes given.
- A Scar to Remember: Though Hrungnir was likely attempting a Taking You with Me by prompting TJ to stab him in the heart (prompting it to explode), he does leave a piece of flint embedded just over TJ's eye. He proudly keeps it as a token of his victory afterwards.
- Really 700 Years Old: Died during the American Civil War.
- Team Mom: Seems to act as a mediator/organizer for the teenage inhabitants of Valhalla's 19th floor.
- Blood Knight: Not quite to the same degree as Halfborn, but she enjoys a good fight.
- Boke and Tsukkomi Routine: The Tsukkomi to X's Boke.
- Fiery Redhead: Very fiery.
- Luke, I Am Your Father: Frigg, wife of Odin, queen of Asgard is her mom
- Official Couple: With Halfborn Gunderson in book 2. However, in Ship of the Dead, she claims that they've broken up, and the fighting between the two increase in violence and intensity. On the other hand, it's implied that they'll eventually get back together at the end.
- Oireland: Hails from the country and has the necessary red hair and green eyes.
- Older Than She Looks: Still firmly in this territory (unlike her other floormates bar Magnus) since she died during the Troubles.
- Relationship Upgrade: With Halfborn as of book 2.
- Ship Tease: Implied to have budding feelings for Magnus with her kisses and frequent showings of affection. Also with Halfborn at the end of Book 1.
- Slap-Slap-Kiss: With Halfborn, see his entry below.
- Smurfette Principle: The only named female Einherjar in the story, until Alex shows up.
- Tsundere: With Halfborn
- Western Terrorists: Mallory was a member of the IRA, and died when she tried to disable a bomb she planted on a school bus when she found out it would have children on it instead of soldiers.
- Boke and Tsukkomi Routine: The Boke to Mallory's Tsukkomi.
- God Was My Copilot: He's actually Odin in disguise.
- Half-Human Hybrid: He's a half-troll.
- Overly Long Name: According to Magnus, "[his name] started with Ks and went on for about thirty seconds." It's a pseudonym.
- An Axe to Grind / Dual Wielding: Has two double-bladed axes.
- The Berserker: Naturally.
- Berserk Button: Do not insult his hometown, or he will fly into a rage that even giants would be no match for.
- Blood Knight: The guy really likes getting to kill things.
- Child Soldier: Left his village to join Ivar the Boneless's forces when he was twelve.
- Disney Death: Mortally wounded while fighting the fire giants, but is healed by Magnus' Healing Factor.
- Genius Bruiser: Halfborn has been waiting a long time for Ragnarok to get started. To pass the time and keep himself sane, he's picked up an impressive number of languages and earned a few degrees in literature.
- Official Couple: With Mallory Keen in book 2. But, In Ship of the Dead, the two seem to have broken up, and are even more violent and sour towards the other than before they had started dating, though there are multiple hints that they'll end up back together.
- Really 700 Years Old: An extreme example since he seems to be the oldest einherjar around, at least that we see. He has been in Hotel Valhalla since the peak of the Age of the Vikings. In fact, he died while protecting Ivar the Boneless during the attack on East Anglia, which started in 865.
- Relationship Upgrade: With Mallory as of book 2
- Shirtless Scene: Often goes bare-chested into battle.
- Slap-Slap-Kiss: With Mallory. She practically abuses and insults him throughout the book, yet at the end of the first book, manages to place his arms around her without her reacting violently as she usually does.
The half-sibling of Sam who dies and becomes a Einherjar near the beginning of the second book. S/he happens to be gender fluid and trans, and as such many of the older norse characters call him/her an "argr" with varying levels of respect and understanding behind it. Never seen without a bright green and/or pink ensemble.
- Action Girl: Whenever she's a girl (which is most of the time).
- Abusive Parents: When she was still alive her dad kicked her out of the house, and disowned her because she couldn't be "normal" and refused to take over the family business.
- Affectionate Nickname: At times he calls Magnus "Maggie." Or "Beantown."
- Archnemesis Dad: Even more so than Sam since Loki interferes in his life more, although in his case it's more like Arch-Nemesis Mom.
- Big Brother Instinct: Since he's male when Sam and Amir are talking about Sam's second engagement, he accompanies them as Sam's male relative chaperone. He takes it semi-seriously.
- The Big Damn Kiss: Kisses Magnus when she thought she was going to die as they trek through the deep snow of Niflheim. He kisses Magnus again after they return to hotel Valhalla.
- Bond One-Liner: "I want a divorce!"
- Combat Pragmatist: Tends to go straight for the throat with magic pottery wire. If the target's too tough for it to decapitate, it makes a great garrotte.
- Deadpan Snarker: At a level to rival even Magnus.
- Defrosting Ice Monarch: Throughout the course of the book s/he warms up to Magnus, Sam, and Halfborn (though the last one is off-screen).
- Discount Lesbians: Gender Flipped...sort of, S/he's getting the Ship Tease treatment with the cisgender male Magnus. S/he's trans and genderfluid, most often a girl but sometimes a guy.
- Doting Grandparent: Learned pottery through her grandfather, and after he dies, she refuses to take over the family business, since she believes her father has exploited her grandfather's artwork. In book 3 we learn that her grandfather was her only family member who truly accepted her gender-fluidity and even encouraged her to embrace it.
- The Fashionista: Alex puts a lot of thought and creativity into his outfits.
- Gender Bender: Changes genders at the drop of a hat but can't do it at will, and can shapeshift to match how s/he feels. Though usually she is female, he has male days as well, and makes sure to notify his friends when a shift happens. One of the strongest signs of her connection to Magnus is his developed ability to tell her gender (90% of the time) without the official confirmation.
- Half-Human Hybrid: As a demigod child of Loki.
- Improbable Weapon User: A pottery wire, which is the weapon s/he died holding. It's enchanted to be extendable and sharp enough to cut through stone.
- Internalized Categorism: Averting this is a huge part of his character and inner strength. Alex embraces everything that makes him unique, even taking the symbol of Loki and adapting it due to its original use as a symbol of change and flexibility. This is the key to his ability to resist Loki's control.
- "It" Is Dehumanizing: Dislikes being referred to as "they" or "it". Though unlike most examples of this trope, she actually dislikes it more because she prefers pronouns referring to her to change like he does. He doesn't like having a "static" pronoun.
- Meaningful Name: Alex is a gender neutral name derived from Alexandros which means "defender of men". Her surname Fierro is Spanish for "iron."
- Mismatched Eyes: Has complete heterochromia. One of Alex's eyes is amber and the other is dark brown.
- Official Couple: Subverted, while the third book ends with Magnus and her having a mutual attraction and acting on it, it's made a point that Alex is a constantly changing person, so there's nothing officially established.
- Red Right Hand: Alex has the mark of Loki tattooed on the back of her neck which Magnus sees during Hammer of Thor. However, she subverts this trope in-verse, explaining to Magnus that to her it symbolizes fluidity and change, just like how she is and embraces it as a part of herself. She also adds that she wouldn't be scared of Loki trying to influence her when shapeshifting like Sam is or allow her godly parent to ruin something good.
- Second Episode Introduction: Alex doesn't appear in the first book in the seriesand is only introduced in the second book, but then goes on to be one of the major characters for the rest of the story. Being a child of Loki, Alex also has the most impact on the main storyline second only to Samirah - a fellow Loki's child - and Magnus himself.
- Secretly Wealthy: Alex's mortal parents are rich, but the only hint of her family's wealth was at least one designer dress in her closet at Hotel Valhalla.
- Subverted. Alex never was interested in commercializing like her father and what money she wants from him, she steals.
- Shapeshifter Default Form: Since he's a child of Loki, Alex could shapeshift to appear more noticeably as whichever gender she identifies as at any time, but makes a point of not doing it since being transexual is part of his identity and she usually sports androgynous looks. Interestingly, Alex's assigned-at-birth gender (i.e. which reprodutive organs he has) is never established, even in a brief scene with her father, who doesn't respect gender fluidity, he never mentions what he sees Alex as, and he's shown to be a petite man, so you can't guess based on Alex's small build. This is completely intentional, since it drives the point that Alex's true gender is whatever he or she identifies as at any given moment. In fact, due to being a shapeshifter, it's implied that Alex subconsciously shifts his entire body towards the gender she is currently.
- She Cleans Up Nicely: Gets made over as the decoy bride for the giants wedding, courtesy of Sif and gets this reaction from Magnus
- Shipper on Deck: Appears to be this for Percy and Annabeth in the opening chapters of The Ship of the Dead, even commenting on how cute the two were together.
- Ship Tease: With Magnus Chase during the quest to retrieve Thor's hammer.
- Spicy Latina: In the third book its revealed that her paternal grandfather was from Mexico, so shes at least a quarter Mexican and is certainly spicy.
- Sir Swears-a-Lot: Apparently she curses like crazy, especially at the very beginning when she's confused and angry.
- Slap-Slap-Kiss: With Magnus, almost as much as Mallory and Halfborn.
- Token Minority: Defied. He's the only gender fluid character in in all of the series, but while explaining his identity she makes it very clear that she's not a representative or ambassador for all trans, gender fluid and non binary people, he's just himself expressing her identity in her individual personal way.
- Transgender: Alex is "trans and genderfluid,". He's considerate enough to let people know what pronouns to use for her at any given time.
- Voluntary Shapeshifting: Does this far more than Sam does, which reflects the fact that she doesn't let Loki's influence shape who she is and won't reject something good just because it's associated with him. However, she defies this in regards to her own body; she doesn't noticeably shapeshift to reflect a change in identity, sporting an androgynous look regardless of what gender she identifies as at any given time.
- You Gotta Have Blue Hair: Alex's hair is always dyed bright green, but her black roots start to grow out when out on a quest for a long time.
The half-blooded daughter of Loki. Although she was handpicked by Odin, Sam faces a lot of discrimination because of her heritage.
- Action Girl: With her badass credentials below.
- An Axe to Grind: Her primary weapon.
- And I Must Scream: Loki has the power to control her completely and totally, to the point where he can tell her to die and she has to struggle to resist him.
- Clipped-Wing Angel: A literal example. While she retains most of her Valkyrie battle prowess and physical conditioning after being kicked out of Valhalla, she loses her ability to fly as a result.
- Defrosting Ice Queen: Starts off as rather cold and angry towards Magnus after getting kicked out of Valhalla. Over time she begins to warm up to him, going from death threats to playful teasing by the end.
- Does This Remind You of Anything?: A girl who because her father (and thus herself) is from a different strain of existence/beliefs than others has to endure some quite racism and xenophobia since everyone is afraid that she'll do something horrible simply because of this heritage? It's quite obvious what real-life Aesop that Riordan is trying to state by this.
- Fantastic Racism: Isn't quite trusted in the Norse world because her father is Loki.
- Flat-Earth Atheist: She doesn't see the Norse Deities as gods; just really powerful people that God created along with angels and jinn. Heimdall agrees with her interpretation.
- In the second book we get a little more information on her religion, and Heimdall actually mentions that he thinks she might be right.
- Flight: She's dreamed of being able to fly in the sky and is excited when she's granted wings as part of the Valkyrie package. Which is why she's very sore when she has to lose them.
- Heroic Lineage: Apart from her father, Sam is also the descendant of Ahmad ibn Fadlan.
- Informed Ability: Sam is described by Magnus as a math wiz, even tutoring kids in the subject, but during quests with Magnus, Blitzen, and Hearthstone in the nine worlds she's not shown using any aptitude with numbers. In fairness, she doesn't really have much opportunity.
- In the Blood: Sam fears this, specifically noting that every time she shapeshifts, her personality becomes more slippery and fluid like her father's. At the same time, her goal is to disprove this trope and prove to others that she is, in fact an honest and loyal individual.
- Like Brother and Sister: She and Magnus are like this.
- Knight of Cerebus: A non-villain example. Samirah's introduction marks the point where Riordan's mythology books have finally directly touched on a recent issue faced in Real Life, namely, the conflict in the Middle East. It's twice briefly alluded to in The Heroes of Olympus series (Frank's mother died in Afghanistan, and Reyna's dad succumbed to PTSD due to participating in the Iraq War), but this is the first time that the issue is touched upon, in full form (the hijab, the arranged marriage, the fear of being accused as a terrorist, etc.). Coincidentally (or not), the book she appears in is the start of a series that's definitely Darker and Edgier than all previous ones.
- The Knights Who Say "Squee!": Has this reaction when meeting Frigg, queen of the Aesir And Mallorys Mother.
- Official Couple: With Amir Fadlan, her betrothed.
- Oxymoronic Being: If you ignore her Flat-Earth Atheist views, you get a Muslim Valkyrie.
- Perfectly Arranged Marriage: She's betrothed to a distant cousin, but says that she has had a crush on him since she was young, anyway. The feeling is very much mutual, and much of the second book focuses on her relationship with her fiancé.
- Averted in the second book, when Loki tries to marry her off.
- Raised by Grandparents: Ever since her mother's death. They're mentioned to be quite strict; Sam has to find many reasons to get around their nightly curfew.
- Smurfette Principle: The only girl in the main party in contrast to Percy's two girls to two boys party. This changes in The Hammer of Thor, most of the time.
- Token Religious Teammate: Of the non-polytheistic kind. She's the only major character in the series (even possibly the entire Rick Riordan universe) who's explicitly stated to follow a faith other than whatever pantheon that the series is focused on. And not the standard western variant (read: Christianity), either.
- Twofer Token Minority: Female, Arab, and Muslim.
- Vitriolic Best Buds: With Magnus.
- Voluntary Shapeshifting: Inherited from her father. She's shown the ability to transform into a deer or a horsefly. Near the end of the first book, she transforms into a lioness to go toe-to-toe with Fenris Wolf himself.
- During Ship of the Dead Alex trains her in order to shape shift without a moment of hesitation and being afraid of Loki's influence.
- Action Girl: The leader of the valkyries must have quite a bit action to merit that status, and it shows.
- Braids of Action
- Brawn Hilda: The first thing Magnus notices about her is that she's "big enough to play power forward [in ice hockey]" and wears her blonde hair in twin braids.
- By-the-Book Cop: She doesn't particularly like Magnus, but the only reason she's hunting them down to such an extent are her distrust of Sam and the fact that the team broke at least a half dozen of Valhalla's rules during their quest.
- Drop the Hammer: Her primary weapon, to the point that she wears a Badass Bandolier full of nothing but ball-pen hammers.
- Foil: To Clarisse La Rue. Both are daughters of war gods with highly masculine physiques, are the leaders of a militant group of allies and were similarly betrayed by their primary love-interests. However, whereas Clarisse was an ungrateful Jerkass and a Blood Knight with Daddy Issues who sought glory for selfish purposes and left her allies to die during the Second Titan War out of pride, Gunilla is a no-nonsense By-the-Book Cop who takes it upon herself to weed out traitors and is willing to sacrifice her life to protect her allies and delay Ragnarök.
- Hero Antagonist: Spends most of the book tracking down the protagonist once he breaks out of Valhalla.
- Heroic Lineage: Is the daughter of Thor.
- Icy Blue Eyes: To match her icy temperament around people.
- Inspector Javert: She hounds Magnus and Sam, believing the two to be working against Valhalla.
- Meaningful Name: "Gunilla" is the Swedish variant of the Old Norse name "Gunhildr", which is derived from the elements gunnr "war" and hilde "battle". Magnus calls her "Captain Gorilla" to mock the pronunciation and her huge build.
- Muscles Are Meaningful: Has the build and athleticism of a power forward and is noticeably adept at combat.
- Sacrificial Lion: Holds off the jotunn Surt all on her own
- Shapeshifting: Able to shapeshift into a bird, which she unsuccessfully uses to spy on the giants.
- Woman Scorned: Given as the reason for her hatred of children of Loki.
- Vasquez Always Dies: The most masculine female character in the cast is also the only named one to be killed on-page.
Margaret and IreneA pair of valkyries accompanying Gunilla in her hunt for Magnus and co.
- Action Girl: They're both valkyries, so it's par for the course. They take part in the final battle.
- No Name Given: Subverted. Shortly after Magnus wistfully realizes he never knew their names, Sam mentions them.
- Number Two: For Gunilla.
- Red Shirt: They die before we get to know their names.
- Those Two Guys
- We Hardly Knew Ye: Die before Magnus even gets to know their names.
- Action Fashionista: His wardrobe includes Paisley chainmail.
- Awesome, but Impractical: His creations. From an expanding duck to a bulletproof tie, Blitz's creations run on this However the last one managed to save his life, by protecting his neck from being ripped by Fenris. He later punches a giant in the face with a chainmail bow tie.
- Black Best Friend: To Magnus and Hearth as his official art shows.
- Crazy-Prepared: He's a dwarf, the whole race runs on this trope. At one point, Thor compliments him for bringing a parachute to a negotiation.
- The Dandy: He has a degree in fashion, and it definitely shows in his wardrobe. He even packs a matching parachute. He even makes fashion-conscious bulletproof vests with matching ties!
- Doomed Protagonist: In book 2 Hearthstone predicts that he'll be mortally wounded. He is, but notice that nobody said he had to die from this injury.
- Emergency Transformation: Magnus exposes him to sunlight to save him from an un-healable wound.
- Heterosexual Life-Partners: With Hearth.
- Improbable Weapon User: Lacking magic or combat skills, he uses Expand-O-Ducks and chain mail bowties as weapons, crossing over a bit with Combat Pragmatist.
- Long-Lost Relative: Sort of. It's explained in series that the gods don't have DNA per se, but due to the fact that Freya is Frey's twin sister, that technically makes Blitz and Magnus cousins.
- Sensitive Guy and Manly Man: The Manly Man to Hearth's Sensitive Guy.
- Taken for Granite: Slowly turns to stone should he be exposed to natural sunlight (light from Freya doesn't count). Magnus uses this to "freeze" Blitzen and stop his wounds from bleeding out and killing him
- The Password Is Always "Swordfish": He charmed a giant bag to size-shift between the sizes of a normal bowling bag and a small mountain whenever the word "password" is said in its' presence.
- Weakened by the Light: A rare heroic example. Because his homeworld is always night, he would slowly petrify should light reach him, unless it's in Folkvanger. To compensate this, he wears heavy amount of clothing.
- Bishōnen: His description ("fair skin, skinny, spiky white hair") is a very obvious indication of this trope, not to mention Magnus lampshading this bit by mentioning that he looks like someone straight from an Anime, a media known for starting this trope in the first place.
- Broken Ace: A necessity. As in Sanderson's The Stormlight Archive, only a broken soul can have the runes inserted into it. Also Truth in Television, since magic in Norse mythology often requires a sacrifice. Odin gave his eye and hanged himself from Yggdrasil just to get his magic.
- Broken Bird: Weaponized, due to the nature of rune-magic.
- Cinderella Circumstances: Although it's unclear how well he was treated before Andiron's death, after it his family got much, much worse.
- Deadpan Snarker: Not bad for someone who only speaks through ASL.
- Disability Immunity: Being deaf, he's immune to Ratatosk's debilitating insults. In the climax, he's the only one who is immune to Fenrir's Compelling Voice.
- Enlightenment Superpowers: His pursuit of rune magic is this. He succeeds, getting Odin to acknowledge him and invites the elf to Asgard for lessons from the All-Father himself.
- Family Theme Naming: With his brother Andiron; both are named for objects relating to fireplaces.
- Growing Muscles Sequence: He uses the Uruz rune in the second book to hulk out and easily overpower a number of skeletal vikings.
- Handicapped Badass: Deaf, mute, and the most powerful mortal sorcerer in any realm.
- Heterosexual Life-Partners: With Blitz.
- Instant Runes: Averted. Hearth has to prep them beforehand and even then he only gets one shot per use.
- Magic Staff: As part of the sorcerer package, he gets a thin, long staff, just before the confrontation with Fenris Wolf. It allows him to draw runes more quickly.
- Maybe Ever After: The ending of "Speaking of Trolls..." (his short story in 9 from the Nine Worlds) implies that he's starting to return Inge's feelings for him.
- Mystical White Hair: Has a short, spiky white hair.
- Only Sane Man: The first to object to the crazy plans that his friends have to concoct to survive their quest.
- Our Elves Are Better: Averted. It's been mentioned that Elves lost their ability to use Alf Seidr thousands of years ago. As a result, aside from his knowledge of Rune Magic (and his natural longevity) he's not much different from a human.
- Parental Abandonment: His parents shun him because he's deaf, and compare him unfavorably to his brother, Andiron. They also hold him responsible for Andiron's death.
- Power-Strain Blackout: Tends to happen to him a lot when he uses his rune magic. It's even lampshaded in one chapter title from the from the first book, Hearthstone Passes Out Even More Than Jason Grace (Though I Have No Idea Who That Is).
- Sensitive Guy and Manly Man: The Sensitive Guy to Blitz's Manly Man.
- The Speechless: Due to being deaf, he communicates through Alf Sign Language, which he also taught to Blitzen and Magnus. It's apparently identical to American Sign Language.
- Squishy Wizard: Technically everyone is squishy without armor, but he otherwise fulfills most of the archetype's qualities if you swap out destructive for support magic. It bites him in the rear when he uses Tiwaz (the rune of sacrifice) to protect Sam from Fenris, nearly dying in the process.
- Averted in the second book, where he uses rune magic to make himself a menace on the battlefield.
- Took a Level in Badass: Odin's lessons have given Hearth a wider variety of magic to use, making him a force to be reckoned with to the point that he overcomes the first obstacle the heroes face in the second book almost single-handedly.
The titular Sword of Summer, Jack is the name Magnus gave Sumarbrandar after he couldn't pronounce the sword's true name.
- Absurdly Sharp Blade: Called the sharpest blade in the Nine Realms. Jack proves it by slicing through the fabric of reality creating a dimensional rift that sucked Surt back to Muspellheim.
- Anything That Moves: If it's a weapon, magical, and (apparently) female, chances are Jack will flirt with it.
- Appropriated Appelation: He happily took the name Jack when Magnus was so exasperated with the situation that he tried to say, "I don't know jack-", cutting Magnus off before he said "shit" or "ass" (it's left ambiguous and up to the reader's interpretation.
- Berserk Button: He's still pretty mad at Frey for giving him up.
- Cast From Hitpoints: While Jack is capable of acting on his own, Magnus will feel as if he did whatever Jack did on his own. At one point, Magnus spends an entire day unconscious from Jack being thrown into a mile tall giantess's brain. Thankfully, this only gets fully applied when Magnus takes hold of Jack again, so he can effective choose a convenient moment of peace to take the drain and [usually] pass out.
- Dreadful Musician: Jack really likes to sing top-forty hits. Too bad he's got a terrible singing voice.
- Empathic Weapon: After Magnus manages to retrieve the sword Jack binds himself to Magnus, acknowledging no-one else as his owner. However, Jack's destiny to free Fenris proves a detriment during the fight to seal the wolf, with the blade barely able to keep itself from flying out and slicing Gleipnir.
- Excalibur in the Rust: Starts off rusted, broken, and covered in barnacles when Magnus pulls it from the lake.
- Gallows Humor: He's full of this.
- Jive Turkey: Kind of strange for sword that was stuck at the bottom of a river for thousands of years to be muttering dude, bro, babe, and other slang words in every sentence.
- Meaningful Name: "Jack", as in, "the Giant Killer"?
- Could also likely mean "Jack of All Trades" - since he's good at, well, everything.
- Oxymoronic Being: It's a plot point that he's a paradox; a weapon designed to not be used as a weapon, a sword that's most effective when it's let go rather than held.
- Talking Weapon: He's fairly chill, for a sword.
Respectable member of elvish society, Hearthstone's father, and a grade-A asshat.
- Abusive Parents: Was one to Hearthstone as a child, and doesn't show any interest in the wellbeing of his son when he sees him again.
- Bad Boss: He's implied to beat Inge, and probably enslaved her.
- Baleful Polymorph: Andvaris ring eventually transforms him into a monstrous dragon who talks to himself crazily.
- Bloody Murder: After the ring turns him into a dragon, it's explicitly stated that the dragon's blood is extremely acidic, which needless to say, made killing him quite a bit trickier. In the end, Magnus manages to get away quickly enough after killing him that he just loses his jeans and nothing more.
- Dragon Hoard: In Ship of the Dead Mr. Alderman turned dragon under the rings influence keeps a hoard of treasure he collected and refuses to move away from it for long periods of time under the fear that someone will come to steal it.
- Evil Makes You Monstrous: The ring Magnus and Hearthstone got in the previous book has slowly turned Mr. Alderman into a dragon. Even after his death, he never returns back into his elf form much to Magnus' dismay.
- Gold Fever: Magnus and Hearthstone pay his wergild by using a magic cursed ring, but the ring is enchanted so that it never provides enough gold and drives the wearer to this. He allows them to give him the ring as the last piece of payment, despite being told of its curse.
- It's All About Me: Refuses to do anything for his son and friends unless he gets something in return- and even then rigs the deal so he gets as many advantages as possible.
- Why Couldn't You Be Different?: The root of his hatred for his son. He even wastes his last words to demand that Hearthstone use a specially prepared chart instead of his sign language when Hearthstone tries to say something to him.
- Would You Like to Hear How They Died?: Tells Hearthstone how his wife, Hearthstone's mom died, and makes it clear he blames him for the death.
A hulder, aka a magical being who's "employed" by Hearthstone's father, Mr. Alderman
- Anguished Declaration of Love: Gives one to Hearthstone when he's about to leave forever and she's been released from his family's service. He doesn't give her much of a reply.
- Conditioned to Accept Horror: She "reassures" Magnus that beatings are only given to the house staff. Magnus notices with horror that she acts as though this is as normal as "burnt cookies or stopped-up sinks."
- Ignored Enamored Underling: A rare heroic version where the hero doesn't try to let her down gently.
- Little Bit Beastly: She has a cow-like tail.
- Maybe Ever After: The ending of "Speaking of Trolls..." (Hearthstone's short story in 9 from the Nine Worlds) implies that he's starting to return Inge's feelings for him.
- Unlucky Childhood Friend: She and Hearthstone are implied to be about the same age, and when Hearthstone frees her from his family's service she tells him she loves him. Hearthstone doesn't seem to return her feelings.
- What Measure Is a Humanoid?: Its illegal for her to try to hide her tail- doing so would get her arrested for impersonating a "real" elf.
Tropes Applying to All Gods
- Age Without Youth: Unlike the Greek/Roman and Egyptian gods, the Norse gods age over time. They restore their youth by eating Idunn's golden apples.
- Bunny-Ears Lawyer: Many of the gods so far are not what you would expect from fierce warrior gods perhaps reflecting the changes of the times. Odin is more of a motivational speaker than Viking Chieftain. Thor prefers to watch and talk about television. Ran acts like a homeless bag lady. Aegir is obsessed with microbrewing. Mimir is a mob boss. Freya is more focused on jewelry and partying than the fate of the world. Despite this, they are not as clueless as the Olympians, less blinded by pride, and dangerously competent when it gets down to it.
- Jerk Ass Gods: Averted, while they have their quirks and egos they are much more helpful and respectful to mortals than the gods of other pantheons. This even includes Loki.
- Though played straight with their methods for imprisoning Loki.
- Also subverted in that they do have some jerkass qualities, namely of the "Hush kids, the grownups are talking," variety with varying levels of condescension. In Book Two, Thor is more interested in partying and celebrating getting his hammer back and completely dismisses the notion of going after the newly-escaped Loki, despite the fact that Loki has gone off to start Ragnarok. In Book Three, during the feast to celebrate Magnus' team successfully capturing Loki and postponing Ragnarok, the gods largely ignore said team while discussing the future and Loki's fate. When Magnus straight-up suggests better methods of imprisonment for Loki that would be less likely to result in his escape, Odin dismissively turns the notion down. However, he does admit that at least part of their blithe response to otherwise earthshaking issues is mainly due to the Norse cosmology being the embodiment of You Can't Fight Fate.
- MayflyDecember Romance: With their mortal lovers.
- Parental Abandonment: Tend not to stick around to raise their demigod children.
- Physical God: The Norse gods differ a bit from the deities of the pantheons in Riordan's other works. Like the Greco-Roman gods, they don't need a vessel to interact with Midgard, so they are capable of having demigod children; They don't appear to possess a divine form like the Greeks, Romans, and Egyptians, being wholly physical; They cannot control the appearance of their age, as stated above; And unlike both of the other pantheons, the existence of the Norse gods apparently isn't tied to western civilization in any way.
- Time Abyss: Some like Freya and Frey are at least 2,000 years old. Others like Odin are are at least 5,000+ since they predate the creation of dwarfs, humans, or the world itself.
- The Archmage: He's the God of Magic, folks. He tutors Hearth in using runes and can shape-shift.
- Blade on a Stick: Gungnir, his personal spear.
- Cool Old Guy: He is surprisingly jovial and kind-hearted despite his menacing position as head of the Norse pantheon. He gives Hearth a staff (thus recognizing him as a fully fledged Rune Mage along with free 90 minutes lessons with Odin), endorses Blitz's clothing line, reinstates Sam as a Valkyrie, and even offers to send Magnus back to the mortal world if he wishes.
- Determinator: Hung himself from Yggdrasil for nine days to learn the secrets of rune magic and stood in line for six days in a blizzard to get a smartphone.
- Eyepatch of Power: To cover the eye he gave up to drink from Mimir's Well.
- Foil: To Zeus of all people. While they're both incredibly ancient and powerful chiefs of their respective pantheons (with amazing beards to match) and egos a mile wide, they otherwise couldn't be more different in terms of temperament. Zeus is an Ungrateful Bastard who does as he pleases and puts the entire world in danger with his arrogance. Odin is a Cool Old Guy who acknowledges the efforts of the heroes and graciously awards them (but he does flaunt the goods in Valhalla's gift shop in the process which includes books and Powerpoint presentations written by him). Their differences are further highlighted by their responses to threats against the world. Whereas Zeus tried to deny the threats of Kronos and Gaea until the evidence was staring him in the face, Odin fully acknowledges the danger of Fenris Wolf breaking free from the start, and actively works towards preventing it.
- God Was My Copilot: Odin spends most of book 1 in disguise as one of his own Einherjar.
- King of the Gods: What he's known for.
- Reasonable Authority Figure: At the end he intercedes on the heroes' behalf and waives their punishment before rewarding them for their efforts (which included a lot of insubordinate action) to save the world.
- Aliens Steal Cable: On top of being the most powerful weapon in the universe, Mjölnir also gets HD cable with full reception. So does his staff, but it gets fewer bars and has a smaller screen.
- Badass in Distress: Singlehandedly protects Midgard against Jotun invasion. But his hammer is missing for the majority of two books.
- Berserk Button: Although no one ever pushes it due to prior warning, do not namedrop Jesus in his presence. Thor once challenged him to a duel and He never showed up. Thor has had a grudge against Him since.
- Big Eater: He eats both of his goats every night for dinner.
- Boisterous Bruiser: Like his mythological counterpart, Thor is rowdy, Hot-Blooded, a Big Eater, and loves a good brawl.
- Burning with Anger: His beard sparks with electricity when he's angry or excited.
- Cool Pet: Tanngjostr and Tanngrisnir (who refer to themselves as Otis and Marvin respectively since their names are too annoying to pronounce) are talking goats who act as Thor's food source on long excursions. Otis is rather mellow and kind-hearted, albeit a bit timid (it took him a day to work up the nerve to provide CPR for the team) while Marvin is much more of a jerk who throws insults at everyone. They revive every morning as long as their bones aren't broken. In a twist, Thor doesn't think of them as cool pets at all. He picked them to pull his chariot specifically because they can revive after he eats them and bemoans the fact that he could have chosen more awesome animals to be his pets, like dragons.
- Covered with Scars: Has a brutish and beaten-looking face and possibly cauliflower ear (Magnus describes him as looking like a long-time boxer).
- The Dreaded: A heroic example. Just about every giant and monster in the nine worlds with a brain is scared of him, and it's his reputation and his hammer that keep the giants from swarming Midgard.
- Drop the Hammer: His signature weapon is the hammer Mjölnir which is missing for nearly two entire books.
- Entertainingly Wrong: Since he can't read ASL, he misinterprets Hearth's snarking, insults, and disbelief at Thor as compliments and mutual agreement.
- Foil: Like Odin, he's a foil to most of the Olympian gods, due to his Jerk with a Heart of Gold status. Despite his attitude and personality, whenever Magnus seems to expect him to act like an Olympian he manages to always be a little nicer. For example:
- He seems to honestly think being given a quest is an honorable chance to prove one's worth (instead of a way to hoist tasks onto another), and usually only gives quests if there's some reason why he can't go himself. Even then, he'll show up (or at least try to show up) when it's possible.
- When Alex calls him out on saying she's "not a proper girl" because she's an argr, he backs down without a fight.
- Despite Magnus' fears, he never takes his anger out on the main characters, instead venting at the electronics in his man-cave.
- Fiery Redhead + Icy Blue Eyes: Pointedly unlike his blond, cleanshaven Marvel interpretation, Thor has vibrant red hair and a beard to match.
- Gasshole: Farts and belches at the drop of a hat just for the check of it.
- God Is Good: Sure, he can be insensitive at times, but at the end of the day, he's among the nicer gods in a world that's filled with Jerkass Gods. Not to mention that he is the defender of mankind, whose job is to constantly protect Midgard from monster and giant incursions.
- Jerk with a Heart of Gold: He can be an ignorant ass sometimes, but his heart is in the right place.
- Jesus Taboo: Has one in place since he's still sore Jesus took his honor without beating him in a fight.
- Knuckle Tattoos: Has Modi and Magni tattooed on his knuckles. They're the names of Thor's favorite sons (who may or may not have been born yet) who are destined to survive Ragnarök.
- Obfuscating Stupidity: Appears to be a cable-watching, no brains, jock type. He's not. This is actually Truth in Television, Thor manage to beat his father The wisdom god of Norse Mythology in a riddle contest. It's just that when your the strongest guy in the Nine Worlds with literally the single most powerful weapon ever forged in your hands (well, it's contended by Odin's Gungnir and the Greek Pantheon's Trident and Master Bolt), there really aren't many problems that can't be solve by a blow of a hammer.
- Person of Mass Destruction: he's capable of pulverizing an entire mountain with one swing of Mjölnir.
- Shock and Awe: He's the Norse god of thunderstorms.
- Sir Swears-a-Lot: His first set of onscreen lines are a series of curses as a giantess tried to drown him. Luckily for younger readers, Magnus's brain seemed to filter them out in exchange for less offensive substitutes since Thor's yelling made his ears bleed.Thor: Mother-grubbing scum bucket!note
- Simple Staff: His primary weapon before receiving Mjölnir, and his weapon when he is sans hammer.
- We Used to Be Friends: He's a bit melancholic when recounting the times when he and Loki used to hang out and go on adventures together. He admits that as much of a pain-in-the-butt Loki could be, he thinks they made a pretty good team and misses those times.
One of the Vanir. God of spring and summer, nature, rain, and fertility. Lord of Alfheim and patron god of the elves. He's also Magnus' father.
- Cool Sword: That Magnus inherits.
- Defiant to the End: He knows how he's fated to die, but he plans to take a few giants with him.
- Disappeared Dad: Like all gods who father half-bloods.
- Easily Forgiven: Fully expects this trope to be averted once he finally meets Magnus face to face, but is proven wrong when Magnus bear hugs him, glad to finally meet his father.
- Hunk: Magnus describes him as looking more like Thor from the Marvel movies than Thor himself, with handsome features, Perma-Stubble, and blond hair that falls to his shoulders.
- Heart Is an Awesome Power: It's explained that war gods like Thor or Odin could never stop Surt and Fenris and all the other monsters from wrecking the world. But as the god of balance, growth, and life, Frey can.
- Improbable Weapon User: He plans to use a deer antler in place of his sword to fight against Surt and his fire giants when Ragnarök rolls around.
- Nice Guy: A very kind and gentle god who lacks the imposing ego and boisterousness of his fellow Asgardians.
- No Celebrities Were Harmed: He's stated to bear a much stronger resemblance to the Marvel Cinematic Universe version of Thor than the real Thor does.
- Power of the Sun: Played with. Being the god of summer, Frey is able to spread sunshine everywhere he goes, a power he passed to Magnus.
- Strong Family Resemblance: Looks a lot like an older Magnus.
- You Can't Fight Fate: He acknowledges how and when he's going to die at Ragnarok and tells Magnus that it's okay as he's already accepted his fate. He then tells Magnus that he's proud of him and to focus on bringing hope to the world as the last Indian summer before Ragnarok.
Vanir goddess of love. Twin sister of Frey and Magnus' aunt. Mother of Blitzen. Ruler of Folkvanger, the Vanir counterpart to Valhalla.
- Amazingly Embarrassing Parents: Blitzen's none too fond of the story of his birth, to say the least.
- Beware the Nice Ones: When she recounts the story of Skirnir, she gets pretty scary. Magnus notes that if he saw her on the battlefield, he'd run the other way.
- Kind Hearted Cat Lover: She adores her cats.
- Lovable Sex Maniac: She's normally quite composed, but show her some dwarven jewelry and she'll do anything to get it.
- My Beloved Smother: She loves Blitzen, but the circumstances behind his conception and her disapproval of some of his choices have strained their relationship.
- Power Glows: Magnus notes that her presence is what makes Folkvanger so warm and bright.
- Really Gets Around: She has a weakness for dwarf-made jewelry, so much so that she's willing to pay for it with a day of marriage. Blitzen is the product of one such "transaction."
- Unwitting Instigator of Doom: Frey was trying to find her when he sat on Odin's throne, triggering a chain of events that will end with his death during Ragnarok.
- Warrior Heaven: Freya is the ruler of Folkvanger, the Vanir home for the honorable dead. It's more peaceful than Valhalla, but the inhabitants are as powerful as the einherjar.
- World's Most Beautiful Woman: Magnus thinks of her as the most gorgeous woman he's ever seen. Considering he's her nephew, it's a little awkward.
The goddess of the sea. She keeps a net that catches many things, including fish, household wares, and souls. She also has the rejuvenating apple of Idun, but because she forgets to consume it, she always has the appearance of a hag.
- Age Without Youth: As a result of not consuming the apple.
- Bread, Eggs, Milk, Squick: Her net catches include: fish, household wares, and souls.
- Making a Splash: She is the goddess of the sea.
- Nice Job Breaking It, Hero!: Thanks to Magnus and Sam tricking her to get the apple, she promises that she and her husband will hunt them down.
- Obfuscating Stupidity: Magnus and Sam trick her like they do with other gods, but there's one thing that she wouldn't do: doing a binding seal.
An elder Aesir whose head was cut off after the Vanir became angry at him. Reanimated by Odin to serve as adviser.
- Bunny-Ears Lawyer: Mimir is this almost to the point of Cloudcuckoolander. He acts more like a mob boss than a wise god, and often gets the two confused.
- The Consigliere: Claims to be this to Odin.
- Equivalent Exchange: The price from drinking from Mimir's well. It can give you the knowledge you seek, but at a price. Odin gave up an eye. Hearth and Blitz had to serve Mimir. Mimir claims true knowledge is only valuable if it is not free.
- Losing Your Head: His head was cut off after the Vanir began to think they had been cheated in a peace arrangement. Odin reanimated it, allowing Mimir to advise him.
- The Older Immortal: Stated to be one of the oldest gods.
- Seer: Has the power to see different futures and tries to guide events to delay Ragnarok.
- The Smart Guy: Stated to be wiser than Odin, and knows more: he absorbs the knowledge of the nine worlds by having his head dipped in the magic springs that feed the roots of the World Tree. His mere presence can increase the intelligence of others, letting them figure things out.
The daughter of Loki and the supreme ruler of Helheim, the realm where those unworthy of entering either Valhalla or Folkvanger go. Has the body of a beautiful woman and crone, all in one. She works for her father, but isn't particularly active.
- Affably Evil: Works for Loki, but like him and her brothers, speaks in an attractive and calm voice. The description of her realm (Helheim) is not too bad, too.
- Face-Revealing Turn: Magnus discovers her two-faced nature when she does something like this.
- Getting Crap Past the Radar: Her being in the series means that Riordan is successful in going past the radar (i.e. "Go to Hel").
- Hell: Duh. Though it should be noted that her realm is not fiery and horror. It's just melancholic and gloomy.
- Never Heard That One Before: She's very aware of the many puns one can make with her name. When she meets Magnus, she sarcastically suggests a few to him such as "Who the Hel are you?".
- Two-Faced: Half of her is very beautiful. The other is very, very not beautiful.
- Villain Has a Point: She's as cold as the world she rules over, and follows her father's wishes. She also points out the fact that by the standards of the Norse afterlife, there are far more people who end up in her realm simply because they did not get to die an honorable death in battle, and that ultimately there are some choices and events that are meaningless in the grand scheme of things.
Thor's wife, and goddess of the Earth. Magnus sees very little of her, but she befriends Alex off-screen.
- Big Damn Heroes: Once the protagonists have the information they need from Utgard-Loki, Sif rescues them from the giants.
- Hair of Gold, Heart of Gold: Literally golden hair, and she turns out to be a fairly decent person.
- Hidden Depths: When Magnus first meets her, he thinks of her as snooty and condescending. Apparently she warmed up while Alex was talking to her off-screen.
- Trophy Wife: Thor refers to her as such, a fact she's very proud of. She thinks it's because she can make literal trophies out of her gold hair.
Guardian of the Bifrost.
- Beware the Silly Ones: He may act like a Phoneaholic Teenager, but according to the myths, he'll be the one to take down Loki in single combat during Ragnarok.
- BFS: His sword is nearly as big as he is.
- Flat-Earth Atheist: He actually supports Sam's belief that he and the other gods aren't actually gods, just very powerful entities; citing that it's hard to see Odin or Thor as gods after seeing them in... less-than-godly personal circumstances.
- Forgot About His Powers: Completely forgot about his time walking the earth as Rigr and blessing marital unions. Sam has to remind him of it.
- The Load: Was this when he, Thor, and Vidar were tunneling into Loki's prison to help Magnus and his friends. The other two gods mention that he was too busy taking selfies to actually help them.
- Nice Guy: He's probably one of the nicest gods in any of Riordan's books. Aside from being extremely friendly, he agrees to help Magnus and his friends try to find Thor's hammer without asking for anything in return.
- Phoneaholic Teenager: He acts like this, taking selfies with just about anyone or anything in the entire universe as it strikes his fancy. And when Magnus and his friends try to talk him into actually looking at things with his own eyes, rather through than his horn (which acts as his smart phone), he complains about everything being three-dimensional.
- Super Senses: He can see anything going on in the nine worlds. It's not omniscience, he can just see that far. Heimdall can also see through things, with the only limitation being that he can't see more than a mile underground, which ends up being a plot point. His hearing is equally insane, as he states that he can hear corn growing thousands of miles away.
The silent Aesir god of vengeance.
- Deadpan Snarker: Not that Thor or Heimdall can appreciate it, a fact that he and Hearthstone bond over.
- The Quiet One: Although he can speak, he chooses not to, opting to use ASL instead. His nickname is the Silent One.
- Improbable Weapon User: Vidar's weapon of choice is a single giant spiked boot that Heimdall describes as being made from every shoe that's ever been thrown away, which is a bit of Fridge Brilliance considering that Vidar is also the god of footwear.
- Revenge: His domain. Magnus finds it weird that a guy who's so quiet and kind would be the god of vengeance. Then he realizes that it makes sense.
Loki's goddess wife. She holds a goblet over her husband to keep venom from dripping into his face.
- And I Must Scream: Her "punishment" is like the kind that you would find in Tartarus. Her husband, the man she loves, is bound with the entrails of her children to a rock while venom drips on his face. In order to avoid the venom constantly hurting Loki, she must hold a goblet over his face, and whenever it misses, it drips in Loki's face, causing extreme agony to him. What's extra worse is that she chose this, and she did absolutely nothing to deserve this fate other than she was married to Loki.
- Break the Cutie: See the above. When one looks at classical portrayals◊, she is definitely a cutie... and when being encountered, thousands of years of watching Loki suffer broke her into an Empty Shell.
- What's more, Loki is able to project himself enough to interact with the outside world. Sigyn is not shown as having this ability... and what does Loki do? Try to atone for his sins? He cheats on her, and Loki outright verbally and emotionally abuses her. Riordan somehow made the trickster god even worse due to how he treats his wife!
- Empty Shell: Hasn't spoken in years. She is utterly broken.
- Extreme Doormat: Does whatever you ask, it's not until the end of Ship of the Dead that she finally stands against Loki.
- Laser-Guided Karma: Gives this to Loki
- Satellite Character: In Hammer of Thor, she only really interacts with Loki via nonverbal communications. In Ship of the Dead, she gives Magnus a look.
- The Voiceless: She never speaks.
SurtKing of the Fire Giants and Lord of Muspellheim.
- Arch-Enemy: To Frey, and, by extension, all of his children.
- Big Bad Duumvirate: He's one of the two main villains in The Sword of Summer alongside Fenris Wolf.
- Disc-One Final Boss: He's one of the main antagonists of Sword Of Summer, but drops off the face of the Earth while Loki takes over as Big Bad for the next two books. He is mentioned several times however in those books.
- Flaming Sword: His weapon of choice.
- Hero Killer: Kills Magnus. He gets better.
- Person of Mass Destruction: One of the last times he came to Midgard, he started the Great Chicago Fire just by making touchdown on Earth.
- Playing with Fire: Naturally.
- The Noseless: Courtesy of Magnus.
- Oh, Crap!: Although he tries to hide it, he's clearly worried when Magnus disarms him and his fellow giants with Alf Seidr.
- Omnicidal Maniac: His life's ambition is to kick off Ragnarok and burn the Nine Worlds.
- Scary Black Man: He has skin as dark as coal and is definitely scary.
- Sharp-Dressed Man: Magnus' first impression of him is "Satan's fashion consultant". Even when riding into battle, he's always dressed to the nines, including a Waistcoat of Style.
- Abusive Parents: As cordial and polite as he may appear to be, he showed no hesitance in willing his children to die when they opposed him.
- Adaptational Jerkass: Loki was far from a Nice Guy in Norse Mythology, but Riordan's adaptation has made him act worse given how poorly he treats his wife in front of everyone. For reference, this is his wife who stayed by his side and tried as hard as she could to keep the burning venom from his face - and she didn't even have to.
- And I Must Scream: For the death of Balder, Loki was chained to a boulder (with his own son's entrails), with a snake dripping burning venom onto his face. Somewhat mitigated in that he is at least able to project himself as a bit of
- Archnemesis Dad: To Sam, who despises him.
- Bad Boss: To Randolph Chase. He constantly belittles and physically abuses the guy.
- Being Tortured Makes You Evil: Granted he was already kind of evil, or at the very least a huge jerk, but being tied up with his own children's entrails while a snake dripped poison on his face for a thousand years evidently made him worse.
- Best Served Cold: The very first thing he does when he's finally freed from his bonds is grab the snake that dripped venom on his face for a thousand years and viciously beat it to death.
- Blood Magic: Aside from being able to control his own children via their shared blood with him, he's also able to establish a connection with Magnus by using Randolph as a medium.
- The Chessmaster: Sets up a complex plan to marry off his daughter Sam, all with the goal of freeing himself from his prison.
- Covered in Scars: His real body has horrific scarring all over his face from the snake's venom.
- Even Evil Has Loved Ones: He's genuinely distraught when he recounts the fate of his sons to Magnus, who were both killed by the gods after Loki engineered Balder's death. It doesn't stop him from trying to kill Samirah and Alex though.
- Evil Is Petty: He freely admits that the only real reason he arranged Balder's death was because Balder's perfection and popularity got on his nerves.
- Faux Affably Evil: For the most part, seems to be affably evil. Then he wipes the aforementioned burning poison on Randolph's face. He notably makes no attempt to hide his more brutal nature, being completely straightforward with Magnus about how he arranged Balder's death out of jealousy and boredom. But because it only comes up when he's asked about it, it's still incredibly jarring compared to the face of him we'd seen until then.
- Gender Bender: Like Alex, he can be either gender as he pleases, though he likely has more control over this unlike Alex, who simply "feels" like a girl at times and like a boy at others. Further more, he's father to Sam and mother to Alex, at the same time.
- Greater-Scope Villain: Manipulates many events of the series, both currently and in the past, despite his imprisonment.
- I Have Your Wife: Keeps a hold of Randolph with the lives of his wife and children. Or so he claims.
- Jerkass Has a Point: As manipulative and evil as he is, he is rather justified in his anger about his children being punished so cruelly for his actions.
- In the End, You Are on Your Own: Magnus tells this to Loki during their flyting competition, where he says that while he has his friends to always back him up, Loki never trusts anyone and is always going to be alone. Even Sigyn turns her back on him. SIGYN.
- Know When to Fold 'Em: After he frees himself, he decides to retreat to Helheim rather than stick around to face Thor, Heimdall, and Vidar at the same time.
- Laser-Guided Karma: Magnus's "The Reason You Suck" Speech.
- Not So Different: Claims this about Magnus, and by extension others, who target people out of jealousy. Of course, Magnus would steal from rich people to survive while Loki killed Balder because he annoyed him.
- Offing the Offspring: At the climax of The Hammer of Thor, he wills Samirah's and Alex's hearts to stop beating and their lungs to stop working. Thankfully, they both manage to resist his influence and make it through.
- People Puppets: He can control his half-blood children through their magical link with him, although Alex has shown that she's capable of resisting him.
- Pretty Boy: Subverted. Loki has a very pretty face when he appears as a projection, but as Magnus mentions, the scars on his face take away from it. Completely averted with his real body, which is terribly scarred and sickly looking from years of imprisonment and torture.
- Sealed Evil in a Can: For his plan to murder Balder, he was bound to a boulder deep underground with his own sons' entrails tying his hands and legs to it, all while a snake drips highly caustic venom onto his face. Whenever he appears throughout the series it is merely a projection of his essence, though he is still able to interact with the world to an extent. He is freed by the end of the second book when Randolph uses the Skofnung sword to sever his bindings.
- This happens again at the end of The Ship of the Dead in which he is captured in a walnut. It Makes Sense in Context.
- Shapeshifter: Sam inherits her shapeshifting ability from him.
- "The Reason You Suck" Speech: Gives one to Magnus, essentially insulting him.
- The Sociopath: Magnus calls him one in the text. Sam actually disagrees, but doesn't think that makes him less monstrous.
- Took a Level in Jerkass: In Sword of Summer, Loki seems (until the last chapter) to be almost apologetic for his actions and to actually be one of the good guys, almost nice. He becomes much more moustache-twirly in the second book. Granted, Loki being Loki, any semblance of good about him has likely been an act, but with Loki it's nigh-impossible to tell.
Utgard-LokiA king of the mountain Jotun and the most powerful sorcerer in Jotunheim.
- Affably Evil: Makes it clear to Magnus that when Ragnarok comes they will be on opposite sides, but has no desire to hurry it up and is genuinely friendly and pleasant to him.
- Evil Versus Oblivion: He helps the heroes get the information they need and makes it very clear that if Ragnarok wasn't at stake he would happily watch Midgard be overrun with giants.
- Master of Illusion: His specialty, his powers are great enough to fool gods. He can make anyone see anything, causing enemies to walk off cliffs or attack their own allies.
- Modest Royalty: Seems to be standard for Jotun kings, as Utgard-Loki hangs out with his subjects in a bowling alley.
- The Older Immortal: Maintains his youth by acquiring apples of immortality, and was around long before the more famous Loki.
- One Steve Limit: Averted, much to Utgard's frustration. Loki is a fairly common name among giants and Utgard was around before the famous one, but is often asked if he is Loki anyway.
- Shapeshifter: Can turn into different types of birds.
- Slave to PR: Has to pretend to be an enemy of the protagonists and helps arrange some Rigged Contests (that he thinks they can survive) while they're his "guests" to please his subjects.
Geirrod, Gjalp, and Greip
Three giants, Geirrod the father, and Gjalp and Greip his daughters, whom the heroes meet at Jotunheim. There is also one more giantess, but she's already killed by Jack a day before Magnus and co. arrive at their home. Geirrod stole Thor's spear, and thus Thor sends Magnus and friends to retrieve it.
- The Alcoholic: Geirrod arrives at home under influence.
- Alliterative Name: And Magnus even lampshades this.Magnus: Do all giantesses have names that start with a "G"?
- Attack of the 50-Foot Whatever: The four are the first giants encountered by the heroes who definitely deserve to be called so. Previous ones have been taking human forms or are human-sized.
- Bizarrchitecture: Their house has a dining room that's taller than the hallway, even though both of them share the same ceiling and door.
- Cute Monster Girl: Averted. Geirrod's daughters are as hideous as their father.
- Outliving One's Offspring: Magnus and co. kill Geirrod's daughters and then flaunt about it. He is not pleased. Of course, he's doomed to die soon.
Thrym III and ThryngaBrother and sister, the grandchildren of the original Thrym who stole Thor's hammer in order to blackmail Freya into marrying him. They were the only survivors of the massacre that ensued when Thor got his hammer back, and they're both out for revenge. The two of them steal Thor's hammer (again), but instead use it as a bride-price in an arranged marriage to make an alliance with Loki.
- Celebrity Resemblance: According to Magnus, Thrym III looks like George Wendt as Norm Peterson.
- Genre Savvy: Although they made a few mistakes, they still learned from the last hammer-marriage deal.
- Instead of trying to marry an enemy, they use the marriage to make an alliance with Loki.
- They plan on keeping the hammer (legally, of course) so they can attack the Aesir once the wedding is done.
- They magically double-check the heritage of the bride before the wedding. Fortunately Sam switched places with her sister Alex.
- Gonk: Both of them are described as being almost comically ugly.
- Modest Royalty: Though Thrynga complains about this, Thrym is happy to spend his time running a bar while waiting for the chance to invade Midgard.
- Women Are Wiser: Thrynga is clearly the more cunning of the two, although she does have a few moments of stupidity (such as trying to use a sword that cannot be used in the presence of a woman).
Fenris WolfSon of Loki. His release from captivity will mark the beginning of Ragnarok.
- Arch-Enemy: To Magnus, being the one who ordered the death of his mother, Natalie.
- And Magnus to him, since as a son of Frey Magnus can restrain Fenris's wildness.
- Beast of the Apocalypse: Fenris' freedom is destined to result in Ragnarok.
- Berserk Button: Anything involving Tyr, presumably because he was a huge part of why the gods managed to imprison Fenris in the first place.
- Big Bad Duumvirate: He shares the position of main antagonist with Surt in The Sword of Summer.
- Compelling Voice: Fenris is able to subtly compel people to do what he wants them to do just by talking without his victim even realizing it. Even worse, he's capable of doing this over insanely long distances, manipulating people who are on the other side of the planet or in one of the other nine worlds. After nearly being tricked into walking straight to his death, Magnus concludes that this is by far the most terrifying thing about Fenris.
- Expecting Someone Taller: Magnus is shocked to discover that the monster feared by all the gods is no larger than an average wolf. However given that practically half of the people in norse mythology are shapeshifters, and given who his father is. It is possible he might get a bit bigger once he no longer chained.
- Manipulative Bastard: May or may not have engineered Sam's recruitment to the Valkyries, as part of his plot to free himself and kick off the end of the world. He really did order Natalie's death to that same effect.
- Relative Button: Loves to push this for both Magnus and Blitz. He nonchalantly talks about how Natalie was nothing more than an obstacle that was in the way of his plans to bring Magnus to him. He also gleefully talks about how he murdered Blitz's father when the dwarf came to replace the rope that binds him.
- Savage Wolves: Fenris is a nasty piece of work, to say the least. And according to Norse mythology is literally the Father of all wolves.
- Super Speed: He moves so quickly that Magnus and his friends can barely react to his attacks, let alone keep up with him. It takes Samirah transforming into a mountain lion to even the field if only a little bit, and even then she's clearly no match for him. And he's doing all of this despite the fact that his back legs are still bound by the magical rope Gleipnir.
- Sealed Evil in a Can: As long as he remains bound, the worlds will keep on existing.
- Leaking Can of Evil: Points out that over the years, his prison has been getting looser and looser, culminating 2 years prior where he finally freed his two of his legs and his mouth.
- Vocal Dissonance: Fenris has an exceptionally smooth, attractive voice, which Magnus notes is just downright eerie coming out of a wolf's mouth.
JormungandAnother son of Loki. Releasing him is another way to start Ragnarok, but he's still (hopefully) put to sleep in the bottom of the ocean.
- Beast of the Apocalypse: Similar to his brother Fenris, his full awakening would signal the start of Ragnarok.
- Eldritch Abomination: All Norse deities qualify, but Jormungand especially, since he's so long as to be able to circle the entire Earth.
- Making a Splash: Played with. While he doesn't directly control the water he's so large he can shift enough water to flood the entire Eastern Seaboard in an instant should he finally wake up fully.
- Our Dragons Are Different: The World Serpent who is long that he can wrap around the entire world. He also loves giant cow heads from Jotunnheim and spits acid.
- Sealed Evil in a Can: Like Fenris Wolf. Ran says that should he be allowed to open his inner eyelids, Ragnarok would start.
RatatoskA giant squirrel who runs up and down the World Tree delivering messages between the eagle at the top and Nidhogg below. It also serves as Hotel Valhalla's security guard.
- Absurdly Sharp Claws: Have claws that are said to be able to gnaw off your insides.
- Killer Rabbit: A giant squirrel. Picture it.
- Make Me Wanna Shout: Emits callings that can torture you. Sometimes psychologically as Magnus finds out the hard way.Ratatosk: You could not save your mother.
- Omnicidal Maniac: Ratatosk is described as being one of the most destructive being in the nine worlds. He's been carrying insults back and forth between the Eagle and Nidhogg in an effort to get them to destroy Yggdrasil and the nine worlds along with it. There's no real reason as to why he wants to destroy the worlds, he just does.
- Poor Communication Kills: Its job is like this. It delivers messages between the eagle and Nidhogg, but those messages are never in their true form.
- Stupid Evil: He trolls the Eagle and Nidhogg despite knowing full well that their actions are endangering the Nine Worlds, and that he himself will die if they're destroyed.
Natalie ChaseMagnus' mother, sister to Randolph and Frederick. Killed on the orders of Fenris, two years before the series began.
- Deceased Parents Are the Best: Was a great mother to Magnus, who had nothing but praise for her. Her love and optimism about her husband is one of the only things that let Magnus let go of his grudge against his missing dad, Frey.
- Missing Mom: Died during a freak wolf attack in her apartment.
- Nature Lover: What drew Frey to her in the first place.
- Sibling Rivalry: She didn't get along with her brothers, and hadn't spoken to them for years before her death.
- Stuffed into the Fridge: A classic case. Her death was planned from the start to get Magnus on the path to retrieving the Sword of Summer.
Randolph ChaseMagnus's uncle. Older sibling of Natalie and Frederick.
- 0% Approval Rating: All of the people who know him directly dislikes him at the very least and completely hates him at the most. Well, except for Loki.
- Absent-Minded Professor: Not actually absent-minded, but he's expelled from Harvard because his crazy theory about the last great Viking settlement in Boston. He's right, of course.
- Aloof Older Brother: Had a conflict with both of his younger siblings that made him not contact them at all, even when one of them (Natalie) was killed and left behind a teenage son. He let said son to wander around homeless, while Randolph himself lived just a few miles from him in a giant mansion. No matter the explanation, Magnus is understandably pissed.
- Badass Grandpa: He is old enough to carry a cane, and yet drives a car like he's still 20-something.
- Drives Like Crazy: Though Magnus isn't surprised a lot, considering that it's Boston.
- Evil Uncle: How truly evil he is is up for debate, but he kept the truth about Magnus from the rest of their family for two years, and is working for Loki.
- I Have Your Wife: His reason for working with Loki is because the latter is keeping his wife and their two daughters hostage.
- Outliving One's Offspring: Outlived his two daughters in a cruiser accident. Actually, they might still be alive, but in Loki's hands.
- Tears of Remorse: Cries after attending Magnus' funeral, as this means that all of that disguising and estrangement for many, many years are futile (he thinks).
- Tragic Villain: He works for Loki, but that's because the latter holds his family hostage. He also had to estrange himself from his sister, who was killed, and nephew, whom he abandoned for two years before founding him, only to lose him again in a horrific manner.
Annabeth ChaseHalf-blood daughter of Athena. Magnus' cousin. For tropes pertaining to her role in Percy Jackson and the Olympians and The Heroes of Olympus, see the character pages for those series.
- Call-Back: This is not the first time a boy she knows has turned up at his own funeral.
- Hero of Another Story: And how! Magnus bets her lunch that his backstory is stranger than hers. The chapter in which this occurs is titled "I Lose a Bet."
- Locked Out of the Loop: For most of the book Magnus has yet to tell her about his father or the fact that he died and became an einherjar. Likewise, his frequent interruptions have left him in the dark about the fact that Annabeth is also a demigod who wants to bring him to Camp Half-Blood. They finally swap stories at the end of the book, and Magnus admits that Annabeth's story is stranger than his.
- Secret Keeper: She promises to keep the truth about Magnus' survival hidden.
Amir FadlanSam's finance and a friend of Magnus.
- Ascended Extra: While only seen in one chapter of the Sword of Summer, Amir plays a larger role in book 2.
- Broken Masquerade: In book 2, after learning the truth
- Go Mad from the Revelation: He struggles greatly to keep a grip on reality after Loki personally confronts him and Sam's family about forcing her to marry Giants, thus breaking the masquerade. Thanks to Sam and company's help though he's able to adjust to the reality of Norse mythology just fine.
- Nice Guy: Gave Magnus free food when the latter was homeless, loves Sam, and treats her friends and family very well after learning the truth.
- Official Couple: With Samirah
- Understanding Fiancé: Helps Sam get flying lessons. After learning the truth about Sam and a brief adjustment period, he accepts who she is and supports her.
- You Can See That, Right?: When Magnus uses the magic of Frey to help Amir see the Bifrost Bridge and permanently opened his eyes to the world of the Norse gods
Annabeth's boyfriend, the demigod son of Poseidon, and a major hero among the Greek and Roman half-bloods. For tropes pertaining to his role in Percy Jackson and the Olympians and The Heroes of Olympus, see the character pages for those series.
- Hero of Another Story: Shows up to teach Magnus the ins and outs of sailing and maritime combat in the third book, but has to head back home to catch up on schoolwork and babysit his half-sister.
- Instant Expert: Being the son of Poseidon, Percy is instinctively skilled at everything water-related. Swimming, diving, piloting a ship e.t.c. Thus he tries to be Magnus' teacher before Magnus ships out to find the Ship of the Dead, but Magnus doesn't have the same aptitude, with his best attempt at diving off the mast of a ship resulting in a broken ankle, with a previous attempt breaking every bone in his body.
- The Mentor: To Magnus, helping him for a couple of weeks.
- Samus Is a Girl: Percy is shocked to learn that Riptide is apparently a female sword and (apparently) very attractive by the standards of magical weapons.
- Sickeningly Sweethearts: Alex calls him and Annabeth this.