--
Justin didn't actually leave.
He made it look like he was leaving, but in truth, he stayed nearby to watch as Ren interacted with the party.
His eyes darkened when Jen, once again, showed her bitchy side. She took one look at Ren and immediately judged him as a delinquent and a waste. She certainly didn't waste time wanting to prove her point.
He could tell that Derek warned her ahead of time. Jen implied that she knew someone new was coming and might've said that she would try to behave, but upon seeing Ren's physical appearance, her words flew out of the window.
Ren, on the other hand, didn't look surprised by her outburst. If anything, from his bland expression, Justin could even say that Ren might be expecting it.
The poor kid is probably used to being judged for something that's out of his control.
Derek tried to stop Jen, but before he could say anything, Ren agreed to her challenge.
