Derk is the older brother of Trevor. He is just as selfish as his younger brother. It is quite possible Derk influenced Trevor to be a bully, as he appears to be one himself. He appeared in the episode Zombie Tea Party 5. Derk is strong enough to be able to bite the top half off a water bottle.
In Zombie Tea Party 5, Trevor introduces Derk, claiming he has been in prison for a while, saying he will be his partner for paintball against Luke. Later, he helps Trevor in paintball, although they ended up losing the match against Jessie and Luke. Derk was the first to lose against Jessie's team after Jessie dodged his shots Matrix-style.