Chara

, also known as the First Child and the Fallen Child, is the first human to ever fall past the Barrier on Mount Ebott into the Underground. This person is who the player is naming at the start of the game, and not the controllable character who is played throughout the entirety of Undertale.

Appearance
is said to have looked incredibly similar to Frisk, down to a "similar fashion sense." Like Frisk, they are of ambiguous gender and appear to have also been around the same age as Frisk when they fell into the Underground. 's SOUL is also the same color as Frisk's.

At the end of the Genocide Route, is seen to be wearing a green and yellow striped shirt, brown pants and shoes. Compared to Frisk, is of a lighter skin and hair color. They have rosy cheeks, open eyes, and a vacant smile, displaying an unusually sunny disposition in contrast to Frisk's constant stoic expression.

Personality
While initially cast in a sympathetic light, Asriel admits at the end of the Pacifist Route that wasn't the greatest person. Asriel says that the reason climbed Mt. Ebott was because they weren't very happy, that they hated humanity; though they never explained why and they felt very strongly about it. It is mentioned that "laughed it off" when they and Asriel accidentally made Asgore ill, by putting buttercups instead of cups of butter into a butterscotch pie they made for him. Asriel states that it was who took control of Asriel's body, picked up their own corpse and carried it out to a human village after  had died. He recollects that when the humans attacked Asriel, wanted to use Asriel's full power to kill them.

The reincarnated is cold and malevolent, in clear juxtaposition to their appearance and apparent age. Their speech is slow and silent. They are shown to display curiosity if the player chooses not to destroy the world.

Main Story
After falling into the Underground, was taken in by Toriel and Asgore as a second child, who treated them with respect equal to their biological son, Asriel. and Asriel became best friends. Monsters spoke of how filled the Underground with hope.

One day, became terminally ill, and their last wish was to see the Golden Flowers of their village. When died, Asriel absorbed 's soul, and carried their body across the barrier to the human's village, where he was attacked by its inhabitants, as the humans had mistakenly thought Asriel had killed Chara. This is later revealed to be in fact a plan by : to poison themself with flowers, have Asriel absorb their soul, and to collect seven human souls to destroy the barrier. Whether their intentions to conceive such a plan were benevolent or not is unclear; Asriel mentions it was who wanted to destroy the villagers when he absorbed their soul and Asriel is who held back and walked away.

's body was originally laid to rest in a coffin in the basement of the castle, where the bodies of the other humans would later be put. Toriel later carried 's body to the Ruins to give it a proper burial.

Neutral Route
When the player gets a Game Over, Asgore's voice can be heard, urging them to "stay determined." The messages heard at this point are identical to those Asgore said to when they were sick and bedridden.

The protagonist may also hear 's name in their dreams. At a certain point in the story, if the protagonist sleeps in Toriel's home, Asgore's voice can be heard, pleading ", please... Wake up! You are the future of humans and monsters." When the protagonist first falls into the Garbage Dump, Asriel's voice can be heard talking to as well.

True Pacifist Route
In the True Lab, VHS tapes of interacting with their family can be played back.

Towards the end of the fight against Asriel, when the protagonist calls Asriel's name to save him, flashbacks of play, showing them after they fell into the Underground, being found by Asriel, and with their family. After the fight, Asriel finally recognizes the protagonist as Frisk.

During the epilogue, Frisk may return to the room containing the coffins of the other humans. They see that 's coffin is empty, and notice mummy wrappings at the coffin's bottom.

Genocide Route
Throughout the route, many characters comment on the protagonist's cold attitude and fail to even recognize them as human.

The only instance in the game where makes an in-person physical appearance is at the end of the Genocide Route. After completing the route for the first time, appears to address the player directly.

states they were brought back to life by the player's power and determination, and that the purpose of their reincarnation was power itself. They identify themself as the very feeling the player receives whenever their stats increase, and propose that the player erases the world so they can move on to the next.

The player is given the choices to "ERASE" the world, or "DO NOT".


 * If the player chooses to "ERASE", will call the player "a great partner."


 * If the player chooses "DO NOT", tells the player that they were never in control. Afterwards a jump scare will occur, in which  approaches the screen with a horrifying laugh . The screen shakes while a loud droning sound loops in the background during the jumpscare.

After the player makes their choice, the attack animation occurs, followed by several red "9"s, both covering the screen. If the game is in windowed mode, the window will shake similar to the death animation of a monster before the game crashes.

Upon reopening the game, the entire screen is black only accompanied by a sound of howling wind. After 10 minutes, will speak to the player, sensing that they want to go back to the game's world, and reminding them that their actions caused its destruction. After asking the player if they think they are above consequences, offers to restore the world in exchange for the player's soul. Agreeing to this trade will restore the world, but will permanently affect the True Pacifist ending. Refusing will have abandon the player in the abyss, only to offer the same choice again after another 10 minutes.

True Pacifist Route
appears briefly after the True Pacifist Ending Credits if a Genocide run has been completed beforehand. If the protagonist chose to stay with Toriel, the after-credits scene continues briefly after Toriel closes the door, showing in place of Frisk turning their face to the screen with red eyes. The game cuts to black, with laughter similar to Flowey's, but slowed down and lower-pitched. Similarly, if the protagonist says they have "places to go," the photograph after the credits will have the face of everyone crossed out, except for, who replaces Frisk.

Genocide Route
After completing a Genocide Route a second time, calls themself "the demon that comes when people call its name." They say that the reason the player continues to recreate and destroy the world is a "perverted sentimentality" they can no longer understand, before suggesting that the player takes a different path if they choose to create the world again. gives the player the "choice" to erase the world again.
 * If the player chooses "ERASE", will once again call the player "a great partner," saying they will be together forever.
 * Choosing "DO NOT" will have tell the player that these very twisted feelings were exactly what they were just talking about.  then reminds the player they sold their soul a long time ago, causing another jump scare, as they destroy the world again.

Asriel
When first fell into the Underground, Asriel found them and took them back to his parents; Toriel, and Asgore. The two of them grew together as siblings and best friends.

Flowey
Flowey, in spite of his inability to feel love, perceives as his partner and best friend. Seeing them as a creature akin to him, he helps them by clearing all obstacles in their way. He says that is the only one who understands him and that they would never give him any "worthless pity."

The Player
only reveals themselves if the protagonist completes a Genocide Route. explains that due to the player's determination, was reincarnated. As the protagonist kills monsters and gains more EXP, seems to grow stronger. refers to the player as their "partner" if the player accepts 's offer to erase the world.

If the player is to complete a Genocide Route a second time, questions why they continuously recreate and destroy the world. then goes on to say that the Player has a "perverted sentimentality" that drives this odd behavior. This behavior is most likely game players' urge to find each and every single bit of information about a game, no matter what it takes, which includes traversing a Genocide Route, even multiple times. Regardless of 's opinion, they further recreate the world.

Toriel
When fell into the Underground, Toriel acted as their mother. She cared for very much, equally as much as Asriel.

Asgore
Similarly to Toriel, Asgore acted as the parent of and treated them as equally as Asriel. It can be speculated that Asgore's "Mr. Dad Guy" sweater was made by, due to their response to checking it while in New Home during a Genocide Route.

In-Game
In several moments throughout the Genocide Route, temporarily disables the player's input and takes direct control of the protagonist. Furthermore, the text that the player sees changes depending on 's voice and thoughts. These narrations are sometimes, but not always, red in color. A list of them can be found on the Genocide Route page. 's perception of various objects also changes depending on the route, most notably the Heart Locket and Worn Dagger, which narrates as being simply "The Locket" and "Real Knife" in the Genocide Route.
 * The first instance of this is during the first encounter and puzzle with Papyrus, where they seem to ignore him and move forward on their own.
 * The next instance of this is prior to the battle with Undyne the Undying, where protagonist turns away, and then approaches Monster Kid aggressively.
 * Another instance of this is during the two encounters with Mettaton, who notices their eagerness to fight him.
 * The penultimate instance of it occurs just as they encounter Sans, and they move forward to provoke him into fighting them directly, and they deal the killing blow to him without any input.
 * The last instance of this is at the Throne Room, where without any input from the player, slays both Asgore and Flowey without hesitation.

Name
"" is likely short for "Character," but there are speculations of its greater significance. For example, The word "" (χαρά) in Greek means "joy", "delight", or "gladness". "Friend" translated from Irish into English is "."

When attempting to name the fallen child "", the response becomes "The true name". Removing the name from a save file results in the name "" being given by default. The child being "fallen" can refer both to the child having literally fallen into the Underground, or to the phrase "to fall from grace" (to become morally corrupt). It is also a word used to describe someone who has died.

The pronunciation of 's name is not yet confirmed, though it is speculated to either be pronounced like "Character" (As seen above) or like "Chart".

Trivia

 * Toby Fox suggests naming the Fallen Child the player's own name.
 * Only if you can't think of anything else.
 * is implied to like chocolate; should the protagonist check the refrigerator in Asgore's home, the text reads " No chocolate. ".
 * While there is no chocolate in Asgore's home, there is a bar of chocolate in the fridge at Toriel's Home; it is possible Toriel kept it in her fridge in memory of 's tastes.
 * The Heart Locket may belong to as the text "right where it belongs" is shown when the protagonist equips it in the Genocide Route.
 * Within the game files, there are sprites of with their yellow-and-green shirt and pants, lacking a face but having shading under the eyes. In debug mode it is possible to have these sprites appear as the protagonist's reflection in puddles and mirrors; it has been speculated that this was going to be normal in a post-genocide run.
 * The music as Chara introduces themselves to the player on a Genocide Route has been dubbed by fans as "The Fallen Child" and "CHARA". What the filename for this is currently unknown.