Lore:

In order to save his friends , mother , and everyone he knows , he killed his dad with a weapon that basically shot out a acidic round right at his dad’s heart , and the acid ain’t normal , it’s built to multiple itself and shred living organisms via their blood vessels and shit

The mask is supposed to be his father during his final moments , as tho he always ruthless and uncaring , constantly beating him , his siblings , and his mother , Alisdair developed a kinda “Stockholm Syndrome” effect to his dad , still regretting down right killing him , and wears his face as shame and to weirdly honor him