Overview
Dave is the main character from Coma, He/she can't wake up, so there's no need to go sleep or use any thing, the player can explore his/her unconsciousness with no interruptions.
Apperance
His/her apperence can change, but mostly times he/she has short hair in purple, with a tilted bangs, and a TV or a test card in his/her chest.
Personality
He/she seems to be quite hooligan, since he/she hits, throws and not has really good words with other NPCs. Also smokes and drinks even not having the legal age for do it (at least in the country of the author).
Past or possible reason to be in Coma
Most probably thing is that her/his hooligan attitude, and his/her excesses only bring her/him a bad health, or had an accident for mixing wrong substances, but that's not really possible since the author or the game itself didn’t specified if he/she uses other kind of drugs than tobacco and alcohol.