UNDERTALE/Asriel

Overview
Asriel is the biological and lost child of Asgore and Toriel. He was wounded before the events of UNDERTALE and died. He later came back as Flowey and started doing the different routes in UNDERTALE. He then became unable to SAVE after the human came to the Underground. He is revived during the True Pacifist route and breaks the barrier after his battle.

Appearance
Asriel is a small, humanoid goat that is a smaller version of Asgore. Asriel wears a lime and yellow shirt, similar to Chara, black pants, and he has a tuft of white hair on his head. In his God of Hyperdeath form, he has a robe similar to Toriel's robe, longer horns, and he has a heart above the Deltarune symbol on his robe. The heart shape is speculated to be Asriel's heart locket, which Chara and Asriel both have. His final form is more geometrical than his other forms. His lower body is heart shaped, his horns, teeth, and claws are longer, and, though this form isn't directly named, he looks like the Angel of Death from the prophecy.

Personality
Asriel's personality is mainly unknown (due to the fact that the only mention of him until the True Pacifist route ends is in the VHS tapes and an odd event that occurs when the player falls into the garbage dump), but he is seen to be very kind and caring, especially towards Chara, caring about (them) so much that Asriel did most anything Chara wanted him to. As shown in the VHS tapes, he may have something to do with Chara's death. In that VHS tape, he said that they were going to save the Underground, and that he was going to get the buttercups. This may mean that Chara and Asriel had planned to have Asriel absorb Chara's soul when they died, so he could go to the surface and gather human souls. Other than that, Asriel is a very docile and unadventurous child before he died.

True Pacifist Route
He isn't seen anywhere except for the end of the route and in the VHS tapes. At the end, he appears as Flowey and calls the player an idiot, before trying to kill the player, only to have every monster that the player befriended show up and try to stop Flowey. Flowey acts defeated before the screen freezes and Flowey says "I can't believe you're all so STUPID." He then absorbs the rest of the monsters' souls and transforms into Asriel. Asriel turns around and says "Howdy!" before introducing himself and transforming into the God of Hyperdeath. He then battles the player for a while before using Hyper Goner to completely eradicate the timeline... and most of the player's HP. He then says that that was just a fraction of his power before his sprite suddenly gets... really wide. The screen goes white and reveals Asriel's final form. The player must select ACT and then Struggle. They must keep doing this until the screen fades to black and says maybe you can save something else. The next phase begins, where you must save all the Lost Souls and then Asriel. Then Asriel turns back into the normal goat child that he is and tells the player that they should just forget about him.

Neutral Route
Asriel is unmentioned (except for a dialogue in Waterfall that is speculated to be Asriel) until New Home, where the monsters around Asgore's house tell the story of Asriel and the first human (Chara). Asgore will then mention him during his battle. That's literally all you see of him in the Neutral route.

Genocide Route
Asriel is not mentioned during this route except when Flowey reveals his identity at the end of the route.