I feel like Zero might be....
Olivia's son. When he mentioned that he was in foster care most of his life, That's when I instantly though that could be a possible story line. Maybe I'm reading too much into him saying that.
I feel like Olivia probably got pregnant with Zero when she was messing around with Pete while trying to get Chase. But when she finally landed Chase, she probably thought she had to cut all ties of Pete which meant giving up her kid. Idk just a thought lol.