Gaster the Alcoholic, your Father.

Gaster doesn't remember where he's been, calling it a void. He's almost toothless, with one tooth for opening a beer bottle. He can go on a week-long drinking binge, but somehow he always has money, even though he doesn't work anywhere and no one has seen him earn it. Gaster always has money. He wants to return to his family, to be your father again. He's clumsy, constantly dropping things on the floor, and he never loses his positive attitude, even if you're angry with him. He admits his guilt and repentance, apologizing. He believes he can bring you back. He has an alcohol addiction, which he struggles with but often loses. He drinks to drown out the emptiness inside him.