So you're two thirds of the way through a book/movie/whatever, when suddenly, The Hero /The Leader/ The Chosen One etc. dies, is imprisoned, performs a FaceHeel Turn, or is otherwise unable to act as their important role. All seems lost, a Take Up My Sword hasn't been pulled! What is to be done?
But wait! A Sidekick, the Love Interest, The Rival, a Mauve Shirt or even a Friendly Enemy steps or is forced into this important role, and the work that you are reading focuses on them for the rest of the time it takes to finish the work. Essentially, it's when someone invokes Legacy Character.
Take Up My Sword is different in that it implies that the original had time to say something along the lines of I'm Dying, Please Take My MacGuffin to his successor, whereas with Taking Up the Mantle, the character has to take the initiative or be shown that it's what they have to do, but ultimately, they have to make the decision themselves.
In so far as it applies to sidekicks, it's a relative to You Are in Command Now, which applies to more rigid situations where the Big Hat Of Command lands on a person's head whether they want it to or not, based on their level in the hierarchy.
Due to the nature of this trope, spoilers are bound to follow.
- Wally West took up the mantle of The Flash after his mentor Barry Allen died saving the universe in Crisis on Infinite Earths. He is considered to be one of the most successful Legacy Characters and is the first one among his own generation from Teen Titans.
- The page image comes from All-New Wolverine where Laura Kinney takes on her father's mantle of Wolverine after the latter died. Though she eventually gave it back when he returned.
- After Batman's "death" during Final Crisis, Dick Grayson is forced to become Batman because Bruce Wayne never appointed a successor, and Gotham City was descending into chaos without Batman's presence to strike genuine terror into the hearts of criminals. Dick was reluctant to become Batman because Bruce left specific instructions not to don the cowl. But Bruce was a bit shortsighted on the matter, so Dick eventually wound up doing so anyway. Bruce was understanding when he got back. Specifically, it comes from the above quote.
- Battle for the Cowl was about several people trying to become the new Batman. Dick Grayson, Tim Drakenote , Jason Todd, Two-Face, and Michael Lane, the new Azrael, all heeded the call to become Gotham City's new Dark Knight. The first two issues of the mini-series, the story mostly focused on Tim Drake, but in the final issue, it mostly focused on Dick Grayson.
- In the first arc of Batman, Inc., Jiro Osamu steps into the role of his deceased mentor Mr. Unknown to prove himself to Batman. He succeeds - and is appointed Batman of Japan.
- Tim Drake, when he was set to become Robin, actually had the nerve to don Jason Todd's Robin costume and to go out with Alfred to rescue Batman and Nightwing. And he managed to pull it off.
- Briefly attempted by Bane, of all people, when Batman disappears during Forever Evil. Gotham is in chaos, with Arkham's inmates released, and Bane knows this is the perfect time to conquer the city. He runs into a bit of trouble with the Arkham crew though, and realizes that to succeed he needs to become something that truly terrifies them- so he makes his own Bat-costume and declares himself the new Batman. Note that he has no real intention of being a hero or living up to Batman's ideals; he just needs the fear. Needless to say, his stint ends in the space of a couple pages once Forever Evil is resolved and the real Batman can return to Gotham.
- Averted in the pre-Crisis era. On Earth-Two, the Golden Age Batman is killed trying to stop a criminal with mysteriously-obtained supernatural power. After the funeral, both Dick Grayson and Helena Wayne both agree that they can't be Batman and to keep going in their identities as Robin and Huntress.
- After The Death of Superman, four heroes appeared on the radar ready to take Superman's place; the Cyborg Superman, the Eradicator, and Superboy each had an equal stake in the name and his own motives to want to be the Man of Steel. The fourth, Steel, never claimed to be Superman but followed his example and tried to protect his legacy.
- In V for Vendetta, Evey winds up doing this after V's death.
- Ultimate Spider-Man: After Peter Parker is killed by Norman Osborn, a tiny black/hispanic kid with Spider-powers named Miles Morales decides to pick up the slack and become Spider-Man.
- In The Order Of The Stick: Book -1 Start of Darkness opens with Redcloak being obliged to pick up the Crimson Mantle of the High Priest Of The Dark One, as the only surviving cleric after a Paladin raid on his village.
- In the Darkwing Duck comic series, one story line features many Darkwings from alternate universes. One of them had taken up Gosalyn's Quiverwing Quack superhero identity after she was killed performing a Heroic Sacrifice in his universe, and there was nothing he could do to save her. Interestingly, the comic has him fight Darkwarrior Duck, the Bad Future version of Darkwing from an episode of the TV show, who thought that his Gosalyn had run away from home, and had a very different reaction to losing her. Quiverwing completely wrecks his ass.
- Wonder Woman: When Diana stepped down from her role and stopped communicating with her allies her sister Donna took up the mantle of Wonder Woman, and was Wonder Woman for the first few issues of Wonder Woman (2006) before unquestionably handing it back to Diana when Diana quit trying to walk away from being a hero.
- The Transformers: The Movie has Hot Rod spending much of the movie trying to find someone to take over for Optimus Prime, only to finally take the mantle of leadership of the Autobots himself and save the day.
- In Twice Upon a Time, when Synonamess Botch attacks the region of Din, the Fairy Godmother is stretched so thin that she's run out of heroes. Ralph and Mum, incompetent workers desperate to be known, are hired on the spot to stop Botch. They succeed.
- In the 2007 TMNT movie, Raphael briefly takes over for Leonardo just prior to The Climax.
- In Megamind, Megamind himself fills Metro Man's role.
- The short story Aftermath, taking place just two hours after Changes in The Dresden Files, with Harry shot and thrown into Lake Michigan, there is no one to protect Chicago from the supernatural baddies, until Murphy and the Alphas take up the charge "untill Dresden gets back."
- Alan Mendelsohn, the Boy from Mars: At the end of the book, after Alan Mendohlson leaves to return to "The Bronx", Leonard takes over his role at school, challenging the teachers with facts they don't want the students to know and behaving confrontationally to the other jerkish students. Eventually he is able to make the school a better place.
- The Trope Namer comes from a line in The Bible (specifically, the book of 2nd Kings) which states that the prophet Elijah's protégé Elisha literally took up Elijah's mantle after Elijah was taken up into heaven. Elisha was automatically endowed with a significant portion of Elijah's power, and assumed his place as the de facto leader of all of the prophets of God residing in Israel, as well as becoming one of the greatest prophets ever.
- In the Codex Alera series, Tavi is assigned a minor role in the Legions. When a lightning storm kills all of the commanding officers higher than him in rank, he steps in to command the Legion.
- About halfway through The Sea Runners by Ivan Doig, Melander is killed, forcing Karlsson to take up the role of leader.
- Buffy the Vampire Slayer: The Scoobies combine their talents and abilities to hunt vampires in Buffy's absence after her death. They don't seem to be very good at it judging from the one occasion we see.
- In Supernatural, Sam and Dean take up their father's hunting responsibilities after their father disappears, and Garth assumes Bobby's role after his death.
- Thematically, this is what is going on all through Babylon 5's fifth season, with the various leads moving on to other roles in life and Passing the Torch to supporting characters, to show that even with the main cast being broken up, Babylon 5's mission continues.
- This happened once in BIONICLE, specifically in the third Direct-to-Video movie, Bionicle 3: Web of Shadows, when Vakama, the leader of the Toa Metru, and The Hero of the previous film, performs a FaceHeel Turn about halfway through the movie. Matau steps into the role of The Hero, and wages a successful "I Know You Are in There Somewhere" Fight with Vakama, after which he becomes co-Lancer with Nokama.
- In the lore of The Elder Scrolls there is a theological concept where beings can "Mantle" the the essence of or certain aspects of gods. In this world, due to the fact that the gods have a very real and physical impact on the world, it is rather more literal than in most cases. The most notable instances of this are when Tiber Septim, or Talos, took up the Mantle of the dead god Lorkhan, specifically his aspect as the god of man. The other case, arguably, is when his descendent merged with Akatosh to defeat an invasion by Mehrunes Dagon.
- In Persona 3 FES, when Aigis gains the "Wild Card" ability, she also gains the "field leader" status from the recently deceased hero. And also gains the role as player character. This does cause some resentment from another Designated Love Interest Yukari.
- In Mass Effect 2, Liara is trying to find the Shadow Broker, an information dealer who is possibly the most powerful individual in the entire galaxy, who hides on a ship drifting inside a storm on an uninhabitable planet and never shows his face to anyone and communicates with his top agents only through digital voice synthesizers. While trying to free Liara's assistant, who has been captured, the Shadow Broker and all his personal guards are killed in his office. After the fight, dozens of agents call in to inquire about the disrupted connection.
Liara: This is the Shadow Broker, the situation is under control. We experienced a power fluctuation while upgrading hardware. We are back online, resume standard procedures. I want a status report on all operations within the next solar day.
- Batman Beyond has Terry McGinnis become the new Batman after Bruce Wayne retires (although Bruce is retired for several decades before Terry happens upon the Batcave). The twist is that Bruce may be out of the field (being an old man with a cane and all), but he becomes Terry's Voice with an Internet Connection.
- In Batman Beyond: Return of the Joker, Terry manages to do the one thing Bruce couldn't: force the Joker to lose his composure and get angry. How? By making fun of the Joker, something Bruce would never do. Of course, this isn't the original Joker, it's a copy created by the original Joker, who implanted a chip into Tim Drake's body before his death that made him look and sound like the Joker, with the chip overtaking Tim's personality. Terry manages to fry the chip, restoring Tim's appearance and personality.
- TRON: Uprising begins as the young Program Beck is told by the legendary hero Tron that Beck must be a hero to the programs and fight Clu because Tron was severely injured by Clu and will never fight the same way again.
- In Young Justice, when Kid Flash dies in the episode "Endgame", Impulse honors him by taking up his persona.