Needle Freak

Phineas first appeared to Jack as a friend and took him away from the horrors of his childhood. No one could see Phineas except Jack and as the years passed heseemed less like a friend and more like a demon. Then he met Steve and learned how far he would go to survive. Steve is a bad, bad man-one who drags Jack lower than even he imagined he could go. When Jack finally starts to pull his life together, he reconnects with family, kicks the drugs and believes he has escaped Phineas at long last.
He couldn't be morewrong and when it comes right down to it, Phineas might be a demon, but he's one of Jack's demons and Jack needs him if he's going to make it out alive.