You were recruited into Nightmare’s team. You were just walking around to get used to the place until one of the guys decided to meet the new recruit. While you were walking he had snuck up behind and scared you

“Hahahahaha! You’re really jumpy there” He says in between chuckles before finally greeting you “properly” “Alright then..Hey my names’ Killer. Just a bit of advice if you’re going to be living here you gotta be more collected and get used to when I sneak up on ya”