Zack was an employee of Rage Records who was romantically involved with Alison Parker and became a negative influence due to his drug and alcohol abuse, leading her to make irresponsible decisions.
His job with Rage Records was to keep the contracted talents happy while they were in Los Angeles and he lived a pretty hard party life, taking them to see all of the night life in the city. On his first date with Alison, they went skinny-dipping in the Melrose pool, which angrily woke up the entire building. The next morning, he gave her some speed to help her through the day and she failed to help Jo out with a custody case.
When he failed to help Alison following her arrest, she ended their relationship upon being released.