He is the real form of Flowey.
Appearance
Asriel looks like both his parents, Toriel and Asgore, having white fur. His eyes have black, slightly slit-shaped pupils and yellow scleras. He wears a green turtleneck shirt with yellow and black stripes, and with black suspenders over their clothes and has purple heart socks and is taller then Chara. Since he is taller then Chara he has horns (Although he slouches).
When he turns into the God of Uber Life, he wears a purple robe with white long sleeves and the Deltarune on front of the robe. He also has a pair of angel wings. His eyes have green scleras with black pupils, He also looks more mature, and has curled horns, and still has his Heart Locket. It is unknown what he looks like when he is in his final form.
Description
When Chara was still alive, Asriel used to bully them and often berated them for being nice. But when they died, Asriel was forced to take them to a bed of golden flowers, as God of Uber Life. The humans on the surface attacked him, thinking he had killed Chara. Asriel did not fight back, and instead showed mercy while Chara tried to take control and attack. The humans, however, did not accept Asriel's mercy and they attacked him until he collapsed into dust.