William Afton suffers from Antisocial Personality Disorder.
For those of you who don't know, Antisocial Personality Disorder(or ASPD) is a kind of mental health disorder where the person who suffers from it tends to lie, break laws, and has no regards for their safety nor the safety of others. The symtoms are as follows:
1.Antisocial Behavior (William Afton not having many friends.)
2.Deceitfulness (William tends to trick people a lot by using fake identities.)
3.Hostility (The term speaks for itself.)
4.Irresponsibility (Sister Location where his daughter died.)
5.Manipulativeness (Signs for this is the same with Decietfulness.)
6.Risk Taking Behaviors (William Afton has put himself in many dangorous situations and he doesn't seem to care.)
7.Aggression (Same as number 3.)
8.Impulsivity (Same with number 6.)
9.Irratibility (Although he dosn't show it often, you can tell he gets angry easily.)
10.Lack of Restraint (Obviously he cannot control his own emotions.)