Mr. Lahey ran the Beacon Hills Cemetery where Isaac also worked. After being trapped in grave by an overturned backhoe, Derek Hale rescued Isaac.
After a fight with his father the next night, Isaac sought out Derek and received the bite, becoming a werewolf.
After the death of his father at the hands of the Kanima, Isaac moved in with Derek.
Their relationship became strained after The Alpha Pack attempted to get Derek to kill the remaining members of his pack, including Isaac. In a misguided attempt to keep him safe - Derek threw Isaac out of his loft. Homeless, Isaac moved in with Scott McCall and his mother.
While attempting to defeat the Alpha Pack, Isaac began to develop an attraction to Allison Argent. Their relationship advanced in fits and starts, culminating in a single night together shortly before Allison's death.
Isaac left Beacon Hills with Allison's father, Chris Argent, and has not been seen since.