Agent Mulder: To Myka's Agent Scully. Far more relaxed than the namesake. It has been said that he is the intuitive side of his partnership with Myka.
Reversed in "Past Imperfect," where Myka is the emotional, impulsive one while Pete is the methodical, logical one. Justified, as in this case Myka is investigating something personal, and Pete realizes he needs to pick up the slack.
Myka: Pete, what are you doing? Pete: Well, I'm thinking like Myka. When something doesn't make sense, Myka tries to make sense of it. But not right now, because she's too emotional, which is where Pete usually is, emotional. Then I thought hey, while you're being me, I may as well be you.
The Alcoholic: Pete is a teetotal alcoholic, having been sober for several years at the beginning of the series. Tellingly, he shows clear signs of panic in "Merge With Caution" when Myka and he switch bodies when Myka was inebriated, fearing that this will cause him to suffer a relapse.
The Atoner: For his relationship-destroying alcoholism. Turns out what actually made him stop drinking was even worse: his drunk driving cost his friend both legs.
Berserk Button: Pete was clearly pissed off enough to want to kill the photographer with the Man Ray camera after what he did to Myka in the "Age Before Beauty" episode. It's probably safe to say messing with any member of his team will get you on Pete's bad side in short order, but hurting Myka in particular, very bad idea. It doesn't help that he mentions that the effects of this particular artifact (turning beautiful women into dying old ladies) disturbs him more than just about anything else he's seen.
Determinator: In "Second Chance", Pete is repeatedly punched by a boxer wielding the collective strength of the 300 Spartans at Thermopylae, but refuses to back down, stating that if the boxer really intends to kill someone, he has to go through him first. Also note that a side-effect of the enhanced strength inflicted whoever he hit with a rust disease, and each hit accelerated the condition.
Dark and Troubled Past: One had been implied for him before (mostly due to his past as The Alcoholic and his divorce from his wife), but it wasn't really elaborated on until "What Matters Most," where it was revealed that he crashed a car when he was drunk, breaking both of his friend's legs
I See Dead People: In "We All Fall Down," Pete sees the ghost of Lena who guides him to the information he needs to find Evil!Artie
Man Child: As Myka and Artie frequently point out.
My Greatest Failure: The one time he refused to pay attention to his vibes was the night that his father died. Pete blames himself for this, since he knows he could have warned him, but by the time he realized how bad the vibe was, it was already too late.
He also regrets his alcoholism and self-destructiveness leading to the breakup of his marriage to Amanda and it's part in his friends death.
With his ex-wife Amanda, though she's now remarried.
Myka Bering (Joanne Kelly)
Action Girl: She can take on four armed Marines while unarmed herself.
Agent Scully: To Pete's Agent Mulder. She has a knack for detail and has been described as meticulous to Pete's intuitiveness.
Artie: This warehouse, well look, the warehouse needs you. Pete, don't touch! It needs your combined talents. He's intuitive and you've got a scrupulous eye for detail. He's scattershot, y'see, and you're meticulous. You look and he leaps.
Arbitrary Skepticism: She's usually the first to point out how impossible whatever weirdness they encounter is. At which point, Pete reminds her what they both do for a living.
Badass Bookworm: Highlighted in the season 3 premiere, where she saves at least four people using her knowledge of Shakespeare plays; three of which are rescued within seconds of each other. Note that she has to do the following to save the victims: look at the page, see the pose and the name of the play, recognize the character, then recite the character's last words, which the victim must say before the page burns out. And she does it every time in less than five seconds.
Does Not Like Men: At least subconsciously, as revealed in "Magnetism". Also hinted at in the season 2 premiere, when both she and H.G. Wells use the same word to describe the men of the 1800's with their misogynistic beliefs, "Neanderthals." Though considering she was in a long term relationship with a man previous to the series, it may be more that she has specific attributes that she desires.
Embarrassing Middle Name: Double subverted. In "Mild Mannered", Myka refuses to tell Pete what it is at first, and finally reveals it to be the rather nice-sounding Ophelia, in a hilarious conversation:
Myka: It's Ophelia, okay? Like from Hamlet. Yes, Ophelia, let the mocking commence. Pete: Ophelia. That's kinda... beautiful. (pause) Can Ophelia boobies? Oh, snap!
Improbable Aiming Skills: In her first case back with the Warehouse just before she was let off of probation, she shot a one inch garbage disposal switch from twenty feet away.
Also, in the season 3 finale, Myka manages to shoot Cecil B. DeMille's riding crop out of Sykes's hand with a Tesla. Note that in "Love Sick", Teslas have been described as hard to aim, due to them being unconventional ray guns.
In "Fractures", she disarms Alice - who is in a fireman's body - by shooting an axe she was holding.
Mama Bear: At least, Pete thinks she would be in "No Pain, No Gain" when she subdues a stalker using a wish-fulfillment artifact while pregnant. Although, after the artifact is neutralized, her pregnancy is undone.
My Greatest Failure: The death of her partner/lover, which, in "Past Imperfect", turns out to have been artifact-related.
Omniglot: Myka understands and speaks a very wide range of languages, including Arabic, Portuguese, Greek, among others. To Myka's dismay, it still constantly surprises the team whenever she displays this knowledge.
She Cleans Up Nicely: While she's not bad looking to begin with, in "The Big Snag", she looks absolutely stunning when they go back to the Indigo Club and dress nice to blend in.
Chessmaster: Of a literal sort, as shown in "Elements". Artie has a chessboard he keeps outside his office and plays against himself for months between moves. Given how Claudia ignores his objections and makes a move half-way through the episode, and then at the end makes the first move of a re-set board, she's also on-board for having this be her role.
Collector of the Strange: Artie likes to take care of the things in the Warehouse, not just store them. He has a near encyclopedic knowledge of every item.
Cool Old Guy: It's frequently mentioned that Warehouse Agents have a tendency to die young whilst protecting the Warehouse. Artie has been working continuously (and occasionally by himself) at the Warehouse for over 40 years. And he's only died once.
Crazy-Prepared: His handbag always seems to contain the most useful artifacts or other objects to help him with almost every predicament he finds himself in.
Death Seeker: Pretty heavily implied in "The Big Snag", stemming from his guilt over killing Leena under the influence of his Enemy Within. He grows out of it, though.
Drives Like Crazy: In "Beyond Our Control", Claudia marvels at how he got his license. Also serves as an inversion as it's usually the spunky younger character that drives like crazy and the conservative cautious older character that freaks out.
Artie: Shouldn't you be in college or something? Don't you wanna be with other people your own age? Claudia: Artie, I'm not my own age. Come on; writing English papers and going to frat parties? Boring.
Calling the Old Man Out: After Steve is killed in the season 3 finale, Claudia calls the Regents (particularly Jane) out for their cowardice and letting their agents take all the risk.
Claudia: You know, I see you and the Regents for what you really are: cowards. Steve was worth a thousand of you.
The Cast Showoff: In "Insatiable", Allison Scagliotti shows herself to be a reasonably talented guitarist and singer. Subverted though, as the sequence in question is relatively unobtrusive and does not in anyway negatively affect the storyline (it's specifically stated to occur during Claudia's down time.)
She showed her chops at the end of "Don't Hate The Player" as well.
Dark and Troubled Past: People thought she was crazy when she started seeing visions of her brother. It turns out her brother really was there; just stuck in another dimension.
Totally Radical: Her dialogue is clearly written by someone with only a cursory knowledge of the pop culture referenced.
Justified. Claudia spent a large amount of her youth in mental institutions, not immersed in pop culture or socializing with her own age group. Most of her knowledge of pop culture is probably just what she gleaned from the internet and tv shows.
Well Done Daughter Girl: Claudia is starving for approval, particularly early on. She gets over this somewhat, later.
Well-Intentioned Extremist: Her introduction has her kidnapping Artie to save her brother, who's trapped between dimensions due to his careless use of an artifact. In the season 3 finale, when Steve dies, she keeps the metronome that was keeping Marcus alive, intent on using it to bring him back, and won't let anyone stop her.
Bad Liar: In contrast to his ability to sense other people's lies, he's a terrible liar himself.
Though considering how he was able to trick Walter Sykes and everyone else he'd gone double-agent, one has to wonder if he's just bad at on-the-spot lying.
But Not Too Gay: Excepting Season 4's "Runaway", Steve's sexuality only comes into play when Pete or Claudia are poking fun at him, and he's never seen with a boyfriend due to being Cursed with Awesome. In the episode in question, his relationship with his ex is built on No Hugging, No Kissing until they have an offscreen sexual encounter at the end.
Synchronization: The downside of the metronome, other than the obvious problem of stopping it. It brought him back to life, but now Claudia, who activated it, feels the pain he would. Once free from the metronome, the effect is removed.
The Spock: Possibly, arguably, but invoked by Pete in the Season 3 premiere. Steve, for his part, plays along with a Vulcan hand-gesture.
Walking Spoiler: If you haven't watched through the third season, do not uncover any of the spoilers in this section. If you already have, make sure you've made it through the second episode of season 4 before uncovering the rest.
Disc One Final Boss: To an extent, MacPherson is this in Season 2. He was the Big Bad of the first season and seemed set up to continue being so, only for H.G. Wells to kill him one episode into the season.
Affably Evil: So much so that, past her introduction episode in season 2, you'd have a hard time believing she ever was evil until the finale. As of Season 3, she's quite firmly on the side of the angels
And I Must Scream: She was turned into a bronze statue, but aware for over 100 years. She seems to have come out of it fairly alright, and just used it to plan.
Chessmaster: H.G. Wells' mentor Catarunga was a literal sort. The two of them played chess every day for years, and H.G. Wells (who was no slouch in this department herself) didn't win once. Catarunga designed a lock for a back door to the Warehouse as a chess game. The game was set up with the player in check; if the player didn't win in 3 moves they were killed. Sykes kidnapped H.G. Wells assuming she could beat the lock, and she still couldn't. She then realized that Catarunga designed it so that the player had to cheat to win.
Commuting on a Bus: During Season 3, her consciousness was trapped inside a metal sphere as punishment, but when she was needed they could let her out again. As of Season 4, this is no longer the case, but she seems to have become much more freelance and so doesn't appear very often
Evil Counterpart: H.G. Wells can be considered this to Myka, even if her scientific leanings are closer to Claudia. She has Myka's Action Girl tendencies, and Claudia's Gadgeteer Genius smarts, but she does not share their good intentions.
Fallen Hero: Like MacPherson, she used to be a Warehouse agent.
Human Popsicle: When she was an agent for Warehouse 12, she voluntarily asked to be bronzed, hoping to wake up to a better world. In a flashback in "3...2...1", there is a brief glimpse of her as this. She remains in this state until MacPherson de-bronzes her in the season 1 finale.
Lady of Adventure: Highly prone to random acts of swashbuckling; at least before she became much more subdued, due to an unusual form of incarceration. Also has a strong English accent, is commonly seen in period dress during her Victorian flashbacks, and still maintains a dignified bearing in present day clothing.
Madden Into Misanthropy: H.G. Wells developed this opinion of humanity, and sought to use the Minoan trident in the season 2 finale to deal with it. She had herself bronzed with the hope that things would have gotten better, but she finds the future far more disappointing than she imagined. She eventually gets better, at least in thinking that Pete, Myka, and Artie are worth saving in the season 3 finale, prompting a Heroic Sacrifice.
Mama Bear: When her daughter was murdered, she invented Mental Time Travel to try and change the past. She failed, but put up a hell of a fight by her account. Claudia tells her that losing a daughter must be the worst pain imaginable. Wells tells her otherwise; what she did to the people who killed her daughter is the worst pain imaginable.
My God, What Have I Done?: Part of her backstory. During her time at the Warehouse, her daughter was murdered. Seeking some way to bring her back, she began combing the shelves for an Artifact that would do the trick. She ended up getting another agent killed, and so asked to be bronzed. Subverted in the season 2 finale, when it's revealed that was all part of the plan.
Nietzsche Wannabe: Due to losing her daughter, she thinks the whole world deserves to die, and rants about how it's gotten worse since she was bronzed.
Of course, her real-life counterpart predicted among other things: tanks, a world war between Germany and England, and atomic bombs. Not to mention, in later work, became apparently disillusioned with the human race and the fate of mankind as a whole.
Omnicidal Maniac: As it turns out in the season 2 finale, not quite omnicidal; she couldn't bring herself to kill Myka, which makes her give up on her plan to destroy the world.
Put on a Bus: Effectively this when she's tasked with keeping the Astrolabe hidden until the threat of Adrian is taken care of. After that is dealt with and the astrolabe returned, she voluntarily distances herself from the Warehouse, hoping to try her hand at a normal life.
Really Gets Around: At least during the late 1800's, while she was a Warehouse 12 agent. It was easier to name who she hadn't been with back then; namely, "Oscar Wilde; and not for lack of trying."
And that's just the men. Who knows how big the list of women she was with is.
Redemption Equals Death: Subverted; she sacrifices herself in the season 3 finale to save the main characters but thanks to a Reset Button she's alive again at the end of the season 4 premiere. Artie is then convinced that she is redeemed, but the Regents aren't as sure.
Sweet Polly Oliver: In this case, the man known as H.G. Wells is actually her brother, used as a proxy since she wouldn't be accepted as a scientist in her time.
Tragic Keepsake: She went back to the Warehouse and broke into the Escher Vault just to steal back her locket, compact, and ring. The locket is revealed to be an ordinary locket, containing a picture of her daughter. The significance of the ring and compact have not yet been revealed.
The Corruption: The bracelet that gave him mobility also completely prevents its user from being able to give or receive love. Unfortunately, they failed to take it from him fast enough to prevent that effect from kicking in.
Evil Plan: His plan to destroy the Warehouse. It works almost flawlessly, the Warehouse is destroyed and H.G. and Mrs. Frederic are killed off (add Jinks to the list and he's the only villain thus far who's managed to kill three major characters); but Jane, Artie, Myka, and Pete are still alive.
My God, What Have I Done?: After Artie hits the Reset Button and changes the timeline, Sykes is "cured" by Gandhi's cloth. Now able to see what he has become, Skyes apologizes to the team.
Portal Cut: Not as gory as the usual variety. Only his hand makes it through the portal, and disintegrates as the rest of him is trapped "between" spaces as it closes. Conveniently, Collodi's bracelet does not disintegrate with him.
Subverted in the season 4 premiere, where Artie hits the Reset Button and he is instead pulled out from the other side by Pete, suffering a fatal concussion in the struggle.
Redemption Equals Death: In the season 4 premiere, after Gandhi's cloak is used on him, he apologizes for his actions and immediately dies afterwards.
Woobie, Destroyer of Worlds: He's an asshole, but it all started because he was in a wheelchair and he got a bracelet that let him walk again...and turned him evil. Then Jane took his bracelet away, meaning he couldn't walk anymore...but he was still evil.
Actor Allusion: He's Brent Spiner playing two versions of the same character, one evil, one...well, maybe not nice, but considerably more level-headed, once the real Brother Adrian is released from the painting along with the rest of the Order of the Black Diamond. Data and Lore, in other words.
Anti-Villain: He does genuinely believe he's doing the right thing.
Church Militant: Works for the Black Diamond Brotherhood, a secret order of the Vatican dedicated to protecting Ferdinand Magellan's astrolabe.
Enemy Within: The Brother Adrian of the new timeline never really existed. He's a manifestation of Artie's subconscious, the evil of the astrolabe given form. The most evil thing Artie could do would be to reverse the effect and create a world without hope, so that is what it drives him to do.
Hypocrite: Gets on Artie's case for supposedly releasing some kind of evil, only to release highly dangerous artifacts which he stole from the Warehouse. In particular, he unleashes Alice Liddell, a Body Surfing psychopath, to take out Artie's loved ones, with no apparent means of controlling her, care for what she'll do after that (not that it would matter; if Artie played ball, it would never have happened), or even any guarantee that she'll honor the agreement (which she ultimately did not).
Averted as it turns out it was really Artie all along.
Improbable Aiming Skills: In the season 4 premiere, he manages to hit a button the size of a nickel with a thrown knife from across the room. He didn't even need any setup time.
Knight Templar: As he tells Artie, "We follow no rules. We do whatever needs to be done."
Not-So-Harmless Villain: Shows a rather scary side at the end of "There's Always a Downside." In the season 4 premiere, he managed to wrestle Pete, a trained federal agent, into a Mutual Kill (which, thankfully, Artie averts by using the astrolabe).
Revenge by Proxy: His modus operandi. Artie used the astrolabe, so he targets Artie's loved ones to get him to use it again to put the timeline back to what it was. While this is technically necessary (he can't very well kill Artie), it becomes this in full when he starts targeting the families of the agents.
For Science!: Perfectly willing to kill off his entire village in order to further his experiments — and to test the Philosopher's Stone on his own brother, sister-in-law, and nephew just to make sure that it worked regardless of age or sex.
Kick the Dog: Immediately upon being debronzed, Paracelsus spots Claudia, knocked unconscious prior, and bronzes her before destroying the machine so it can't be reversed. Just in case you might of thought he didn't deserve what he got.
Living MacGuffin: Sutton and his family broke him out of the Warehouse's bronze sector so he can undo their immortality.
Insistent Terminology: She is Mrs. Frederic. Not "Mrs. F." And certainly not "Irene," unless you're a close friend or superior.
No Immortal Inertia: The moment the Warehouse explodes, she collapses, dies, and decays very rapidly. Subverted later in the season 4 premiere after Artie hits the Reset Button
However, this can be justified by the fact that her life force is tied to the Warehouse.
Also, it would appear that this only happens if something bad happens to the Warehouse. In the season four finale, she's purposefully disconnected from the Warehouse (which almost definitely is what makes her immortal), and she doesn't seem any worse for the wear.
The Omniscient: Has a tendency to suddenly materialise when she is being spoken about, and always seems to know virtually everything about what other characters are doing. This, combined with her ability to appear and disappear randomly, her intermittent amorality (or at least ruthlessness) and her use of a very terse form of Spock Speak, is the reason why she is able to scare the crap out of most of the other characters.
The Quiet One: She does speak, but only when necessary. Most of the time she just gives people a rather spocky version of the Death Glare.
Season 4 sees her with a more talkative role, usually with Jinks. Whether this is guilty over Steve's death, responsibility/shared burden of his double agency, something else, or just coincidence is an exercise for the reader.
Really 700 Years Old: Mrs. Frederic is bonded to the Warehouse and if it dies, she dies. Confirmed in "No Pain, No Gain" when Claudia meets her older-looking grandson.
Reasonable Authority Figure: Despite her stern and scary nature, she does value the input of her Agents and is willing to give them the benefit of the doubt in certain situations.
Screw the Rules, I Make Them!: When Mrs Frederic goes to war, she doesn't adhere to the Geneva Conventions. Although it is never stated outright, she demonstrates that in her mind, she only really has one rule; what she wants, she gets. Given that she is a Regent, it is also implied that she justifies this internally with the belief that the ends justify the means.
Skunk Stripe: Gets a stripe of gray hair in season 4, a result of the Warehouse being destroyed then restored through time travel.
The Stoic: She generally doesn't like displays of human emotion directed towards her, even if they are positive; which is another element of her alien demeanour.
In the Christmas special at the end of Season 3, Pete made the mistake of giving her a hug. She didn't react well.
Take Up My Sword: Though not yet, she's clearly decided that Claudia is going to replace her sooner or later, and events in season 4 convince her to step up preparations for that.
Who Wants to Live Forever?: A mild case. As seen in "No Pain, No Gain", she doesn't complain about it, and she isn't actively trying to get rid of it, but she has lived long enough that her grandson is old enough to look like her father.
Dropped a Bridge on Him: He dies rather abruptly (and brutally!) about halfway through the second season, early in the episode "Vendetta", after having been absent since about halfway through the first season.
Da Chief: He's introduced as the head of the Regents.
Reasonable Authority Figure: When Pete inadvertently comes close to blowing the Warehouse's cover by arousing a doctor's suspicions, he gives Pete a chance to choose the best option of dealing with the problem, letting his vibes inform his judgement.