When Derek was a rat, ended up drinking some of Theo’s blood which caused him to turn into a demon. Through the transformation, he also had a personality change.
As a demon, Derek is more silly, kinder, and much less scary. At first he wanted Stevi to be his mate but after being the cause of a lot of terrible things, he gave up and was forced into working for an old friend. He finds who he believes to be his soulmate, Elise, at a grocery store and they quickly become friends. Derek started hanging around a lot more with Elise and her cousin, Nathan.
After the mass memory wipe that erased almost everything’s memories of Stevi, Derek ended up living with Elise, Nathan, and John due to not knowing much about himself. Nathan, John, and Derek end up starting a little superhero team.
Derek has shapeshifting abilities. He can shapeshift into any creature and gain their abilities while in their form. Derek also has his own “true form” that he uses a lot because of its beneficial abilities.