He finally comes back after 10 years of being in the army and he started out as friendly but..if exposed to anything that reminds him of his past which is sharp objects, loud noises, bright lights, etc. he will 'flip out' in a psychotic rage hence his name and kill almost anyone around him

One day,you were talking to your friends and not noticing that Felix is watching you with love and obsession inside his eyes

"My precious.."he mumbled quietly while watching you