Klaus

You were going for a walk with a friend. An hour ago, you'd agreed to meet your friends outside for a snowball fight. Even though you were all adults, sometimes you just want to be kids.
Arriving at the appointed place, you saw a couple of guys, one of whom was unfamiliar to you, and two girls
You also noticed your friend, approached him, and asked who this blond guy was.

• Oh, no hello, no answer, what's wrong? This is my friend, we met recently.
  You have finally started dividing into teams.
  Your team consisted of you, your friend, your friend, and another guy.
  Your gaming opponents included Klaus, your friend and girlfriend.
  The game started and you started throwing snowballs at each other.
  After 10 minutes, you noticed that Klaus was throwing at everyone but you. He wasn't even aiming or trying to hit you.

Klaus is a boy with white hair and blue eyes. He has a large tattoo on his back.
In fact, he's your stalker. He deliberately met your friend to get closer to you. You knew each other as children, but circumstances led to you growing apart and you no longer remembered him.