Chara

Chara is a human from the Undertale universe. They were adopted by the royal family of the underground, but now live in the Furthest Ring with Cyrus, training as his apprentice.

Fallen Down
A long time ago, Chara fell into the Underground. They were found by Asriel and taken to Asgore and Toriel, where they were adopted as part of the Royal Family.

The Plan
Later on, Chara came up with a plan to break the barrier trapping the monsters underground. They ate Buttercups so that they would die and Asriel could absorb their soul. Asriel crossed the barrier, but refused to fight any of the humans. He fled back underground and died, leaving Chara dead without a host for their soul.

Dead
After the plan failed, the Annoying Dog found Chara's soul, and caused it to be bound to any player who enters the Everything is Connected Multiverse.

Gaster Timeline
In an alternate timeline, Chara's soul was destroyed by Gaster. This timeline was erased by Daniel, however.

In the Johto Region
In Pokemon Bisque, Chara makes a cameo in a house in Blackthorn City, where the attic has a Snorlax in it. Attempting to wake up the Snorlax will make the player try several classic methods of getting it to wake up, but none of them work. Chara then offers the player one more option... A drastic method, but it WILL work. Choosing yes will cause the player to put on a chicken hat, do a silly dance, stick their tongue out, make funny noises, spin in circles, grab the nearest megaphone (which is in China) and yell into it "I'M ! COME AND GET ME, ALBERT!", spin around once more, fall to the ground, and black out. When the player comes to, the Snorlax is awake.

In the Alternia Region
Later on, Chara was bound to the player of Pokemon: The Next Chapter. Chara lent the player the power of Determination, and watched their journey. However, after Daffy's Chi was absorbed by the player, Chara used this power to awaken from death and take the Soul Infinity Stone for themselves. They created a pocket dimension and used that to test out their power.

However, after a while, Bugs and Daffy returned with Yubam Endall, threatening to destroy the universe unless Chara returned the Soul Gem. They did, but Gaster appeared after to fight the player. They were teleported out of the pocket dimension before Yubam destroyed it. After the fighting was over, Cyrus appeared and took Chara to the Furthest Ring to train them as his apprentice.

Powers
Chara has a red soul, letting them use Determination as Soul Magic. When they possessed the Soul Infinity Stone, they also had powers over Chi.

Determination
Chara has the power to Save and Load the world. However, if anyone else has higher determination, their power takes priority.

Trivia

 * The name "Chara" is short for "character".