Bob's got the power to perform a Fusion Dance with other people, with or without their consent. When he does, he takes from them their personality and memories. Whether or not the people live on inside his own mind varies from work to work. Generally speaking, this sort of thing kills the absorbee, although exceptions exist.
Of course, taking others' personalities and memories can lead to problems — Occasionally, Bob has a Loss of Identity due to remembering things or behaving the same way that Alice, Carol, Dave, Eva, Fred, Gina, Harold, Irene, Johnny, Kim, Leon, Melissa, Nick, Ophelia, Pat, Quinn, Ronald, Stella, Travis, Ursula, Viktor, Winona, Xavier, Yolanda, and/or Zack did, in addition to his own identity.
Compare Mental Fusion, where both Alice and Bob are still alive, but a mental link is formed between them.
See also: The Assimilator, Power Copying, Transferable Memory, Memory Gambit and Merger of Souls.
- The various fusion methods in Dragon Ball Z. There's the Namekian fusion, in which one of the participants remains as the dominant personality but gains the other guy's memories, and the fusion dance and Potara earrings, both of which create a new entity that has all the memories of both participants, and a blend of their personality traits. There's also Super Buu's absorption, which also grants him traits of his victims (for example, after absorbing Piccolo, he becomes far more intelligent).
- Hellsing: Alucard keeps the memories of all those he devours. Because, when consuming their blood, he also takes their souls. For the same reason, Seras absorbs Pip Bernadotte upon his death. That she does so with Pip's consent seems to result in the two sharing a different bond to Alucard's with his victims.
- In Grant Morrison's run of Doom Patrol, there is a supervillain called Fog whose power is pretty much this. He can swallow people alive, but all of the people he's eaten still exist as different personalities inside him, and they're constantly arguing with him and with each other.
- The Superman villain Parasite has this. Usually it's a temporary awareness of their memories, but on one occasion he absorbed a scientist and found himself Sharing a Body with them as "Doc Parasite".
- Rogue has this as her mutant power.
- Multiple Man is capable of doing this to his duplicates, should they go off and live their lives away from him.
- In the Harry Potter fic "Xerosis," Death sends Harry back in time with instructions to kill as many muggles and vampires as he can and to help him with that, Death gives him the ability to perform a kind of Dementor's Kiss that absorbs the memories, abilities and sometimes powers of the victims, killing them in the process.
- When an immortal is devoured by another, the surviving immortal gains all the other's memories.
- The novels later give us a number of homunculi that can assimilate anyone who drinks their "water" into an ever-growing hive-mind. Two homunculi "twins" actually have different stances on the practice too. Sham couldn't care less about each vessel, only caring about his own survival. Hilton, on the other hand, is fiercely possessive of her first vessel, Leeza. Considering that she was young enough to be raised as Leeza and considers Leeza's father (and her creator) Huey her father, maybe it makes sense. It's also implied that reverse-Identity Absorbtion is possible with them.
- The Commonweal has the Entelech, who have a necro-parasitic life cycle, who have to fall in love with, and then eat, a sorcerer, consuming their minds over hundreds of years.
- A dark spell mastered by the evil wizard, Fistandantilus, in the Dragonlance series, allowed him to absorb the youth and vitality of another, thus granting himself quasi-immortality. When Raistlin tricks him and turns the spell back at him, seeking to thus absorb his knowledge and power, the result seems to be something of a Fusion Dance, and when the smoke clears... it's somewhat unclear who actually won. Raistlin is personally certain that he is, in fact, Raistlin, but when he later runs into the All-Seeing Historian Astinus, he refers to him as Fistandantilus, claiming to have carefully recorded the battle and the outcome. Assuming he is right, Fistandantilus actually did manage to absorb Raistlin's spirit, but was overpowered by his mental strength and unbreakable personality, ultimately becoming subsumed...
- This is done by complete accident in My Next Life as a Villainess: All Routes Lead to Doom!. When Sirius Dieke became deathly ill as a child, his mother coerced a mage into performing a dark magic ritual to transfer his consciousness into the body of his illegitimate half-brother Raphael Walt (with Raphael's mother being used as a Human Sacrifice in the ritual). Since Sirius was basically already dead at this point, Raphael simply gained all of his thoughts and memories but functionally remained himself, masquerading as Sirius for years to avoid being killed.
- Wild Cards has early Ace Brain Trust, who worked with the Exotics for Democracy by entering hostile situations and duplicating the minds of political and scientific geniuses. The first time her powers manifested, she nearly went mad, and needed the help of Doctor Tachyon to create mental constructs to filter out each personality — constructs which finally collapsed when she was subjected to questioning by HUAC, resulting in her being committed to an asylum.
- Agents of S.H.I.E.L.D. has an episode end with two people absorbed into a massive chunk of Gravitonium. They're shown to still exist within the substance, driving Absorbing Man insane with their arguing when he tries to absorb a small piece. However, when Glenn Talbot absorbs a far larger amount, he mentally dominates the two into obedience, and takes to further absorbing people through tendrils of Gravitonium to take their powers and knowledge for himself.
- In an episode of The Adventures of Superboy, Lana Lang encounters an alien being who is from a race of beings who have no identities of their own, so they survive by taking the identities of others, becoming perfect duplicates of them. The alien starts the process of becoming Lana, a process which would end with Lana's death if completed.
- Olivia absorbs John Scott's memories in the first season.
- In season four, a serial killer absorbs the happy memories of his victims which destroys their brains after a while. He ends up absorbing his final victim's morality as well, leading to a My God, What Have I Done? moment, followed by suicide.
- The first season has a shapeshifter who can absorb a person's memories and assume his/her appearance while also retaining its original memories. This process normally kills the victim.
- In the second season, we find out that the protagonist 'Audrey Parker' actually has all the memories and the personality of the real FBI agent Audrey Parker up to the point that they act almost identically and use the exact same phrases when placed in similar situations. She does not remember who she was before this happened. We later find out that the same thing happened about 30 years ago with Lucy Ripley and might happen every time the Troubles come back.
- Heroes: This happens to Sylar after Matt pushes Nathan's memories into him. For a while, he's just Nathan, and then he goes through a phase where he switches back and forth. Eventually, he is a fused personality with the memories of both.
- The Highlander franchise has immortals killing each other for memories, personality traits, and power. However, there doesn't usually seem to be any personality issues, except for rare mentions of a 'Dark/Light Quickening', when an otherwise good immortal absorbs one too many evils, or vice versa. Other than being a plot point for a single two-part episode, the possibility is never mentioned again.
- In Kamen Rider Kabuto, the Worms take on the memories as well as the forms of their victims before killing them. (Not that killing them triggers this, but it is their MO.) More than one has said things to the effect that the person they mimicked would live on in them so killing the original was no loss. We even get two instances of Worms forgetting they're not the person they imitate, prompting an "are all Worms evil or can some gain humanity over time?" debate. Not that Worms are inherently bad — some have been around since before the meteor that brought the bad guys, and don't go around killing people.
- Star Trek: The Next Generation:
- In "The Offspring", Data downloads his daughter's memories into himself after she breaks down.
- The Borg do something like this, in particular with Picard in "The Best of Both Worlds", but the victim is generally subsumed by the sheer number of existing drones and the willpower of the Borg Queen herself.
- A writeup of the coming RP supplement for the Divine Blood Novels for the Kitsune has them able to do this. The soul and mind of the individual live on in the body and the kitsune can take a form similar to their original appearance only with foxy adds. Following a gestalt, the kitsune has to spend some time before doing it again as their body, minds and souls settle down to a healthy level. Kitsune who absorb unwilling minds and/or don't wait after each gestalt eventually become insane and incapable of reproduction among other things.
- At the start of Kingdom Hearts II, the self-aware Nobody Roxas has to return to being part of The Hero Sora and clearly feels that this will happen to him. He is seen again a couple of times, when some particularly powerful psychic influence causes him to re-emerge briefly, but Roxas was basically correct to consider the merge to be his own death. Outside of those moments, the only trace of him that remained showed itself when Sora found himself crying when he said goodbye to Roxas' friends, who he thought he'd only just met.
- Alex Mercer in [PROTOTYPE] does this and can perfectly mimic people he's absorbed, right down to their voice. He even does it so well that he doesn't realize that he's not actually Alex Mercer. He's The Virus itself, and Mercer was just the first identity he consumed.
- In SaGa Frontier, when either Blue or Rouge kill the other, he gains the other twin's personality, memories, and knowledge of magic.
- Red vs. Blue has the A.I.s personalities that do this, though technically they were a whole personality to begin with. They form together, absorbed into the Epsilon fragment's mind.
- This is one way to get rid of an alter for people who have dissociative identity disorder.