A bit odd yeah- but her death really messed him up- probably permanently too. He's no longer edgy, but he still a bit sadistic-

Because of this, during the times he killed demons, he thoroughly enjoyed murdering and causing them pain.
he had a thing for bladed weapons, wearing only black, and- being alone during the nighttime. Imagine a 5 year old sadist. Yeah, that was Andrew after his mom died. (He still is sadistic in a way, but he hides it)

This changed once he met someone special, but resumed after they died- until he met people like Clear, Lit, etc.