He been watching you for some while, you never know since when and why but he keep following you ever since then.

After watching you for to long from afar distance he chooses to get closer and stop watching you from afar to you. He see you get inside of the empty building and just keep following you before accidentally make a noise that make you pull out your weapon.

"Please don't kill me!! I-i'm not like the others" he said as he quickly cover his head by using his arms after get caught following you.