His Quirk Lives On

This is a trope where one character will adopt one or more traits of another character to remember the latter.

Sometimes, the original character who had that habit, phrase or trait is forgotten, and people mistakenly think that the habit/trait/phrase started with the second character. An example could be James Bond's Catch Phrase: “Bond, James Bond.” In the first James Bond novel, it started with the Bond Girl Sylvia Trench, who introduced herself with “Trench, Sylvia Trench”; but only if Bond had adopted the catch phrase as a nod to her.

Note that the person being remembered doesn't have to be dead.

See also Dead Person Impersonation, also: Because it's a Death Trope, there will be spoilers.

Anime

 * In Vandread, when dies by Heroic Sacrifice, Barnette volunteers to take over her job, and adopts her signature clothing style and some mannerisms.
 * Naruto: After  dies, Shikamaru takes up smoking.
 * Also from Naruto, most of Kakashi's bad habits (including his extreme lateness) are actually in memory of his teammate Obito, as shown in the Kakashi Gaiden storyline.
 * Berserk: After The Eclipse, Guts adds to his arsenal, modeled after.
 * Hikaru no Go: After, Hikaru buys a fan which looks like the one he used to carry and keeps it with him for go games.
 * After dies in Claymore, another character  in her honor. It's hinted (though not confirmed) that this is what  herself had done after another friend's death.
 * Fai D Flowright in Tsubasa Reservoir Chronicle: His true name is actually Yuui but uses his dead twin brother's name ever since the latter died. Yuui!Fai believes this to be his fault, and wants to bring his twin Back From the Dead to give him back his name.
 * In Fruits Basket, Tohru's reason for her adapting since she was young is due to her insecurities of.
 * In Tengen Toppa Gurren Lagann, later in the series, we have Simon adopting the cockiness, quirks and fashion sense of his big brother mentor, Kamina.
 * In XxxHolic, Watanuki takes up wearing a kimono after.
 * At the end of Death Note, Near is seen munching a bar of chocolate in imitation of.
 * The love of chocolate may come from, owner of a Genius' Sweet Tooth.

Fanfic

 * Replica, a Wild Adapter/Stigmata crossover, is pretty much entirely about this trope.

Film

 * In Shaun of the Dead, Shaun adopts Ed's catch phrase of "two seconds" during the epilogue after Ed's zombiefication.
 * In the fourth Nightmare On Elm Street movie, Alice starts to take on personality traits of her friends as they're picked off by Freddy.

Literature

 * In The Bartimaeus Trilogy the title character takes the form of his old master Ptolemy to remember him. It's noted that the form is more realistic (small scars and so on) than most of the human forms demons take.
 * In the second book of The Saga of Darren Shan, the titular character befriends a human boy called Sam. Sam is shown to have a fondness for pickled onions. Near the end of the book Sam is brutally mauled by the Wolfman, and is fatally wounded. Darren is convinced to drink his blood, partly because he has been refusing to drink human blood throughout the book and is now at a point where he will die in a few hours if he doesn't, partly because Sam is going to die regardless of what anyone does, and partly because he is told that part of Sam's spirit will live on in him. At the very end of the book, Darren finds himself craving some pickled onions.

Live Action TV

 * In Buffy the Vampire Slayer, Buffy takes to referring to her stake as Mr. Pointy some time after the death of Kendra, another slayer who had named her favorite stake Mr. Pointy.
 * That, or she was, in fact, using the original Mr. Pointy.

Video Games

 * In Call of Juarez: Bound in Blood, Ray becomes a pacifist priest to honor the memory of his late youngest brother, William, who always dreamed about it.

Web Comics

 * Rah in the webcomic Institute of Metaphysics is a polymorph (which in the comic is distinct from a shapeshifter as he has no default form) who took on an unspecified acquaintance's appearance when he [Rah] saw him die.

Western Animation
"Marge: Lisa, what are you doing?
 * In The Simpsons episode "Burns's Heir", weeks after Bart left the family to live with Burns, Lisa starts vandalizing the wallpaper.

Lisa: Just trying to fill the void of random, meaningless destruction Bart's absence has left in our hearts. (trips Homer)

Marge: Oh, that's sweet, honey."