She definitely gave him no ground to move on her terms of their studying, evidently even his counselor was enjoying her tormenting of him. Most people would've told her to go and die as well, but the way these cheerleaders had teased the girl, he decided to stick it out with her, the obvious annoyance in Serena's voice with his decision to eat with her was apart of the reason why he chuckled at them, as well as the overly sarcastic remarks that Mia shot back at them. The ladies didn't seem too happy with the fact that he wasn't joining the girls in razzing her, and seemed to lose their interest in continuing the conversation. 

"Look ladies, just go do your thing, and I'll talk to you guys later about the party, I might have to study instead of party.. My counselor's not too happy with me, neither are most of my professors," He said to them, getting them to shoo away for now. After they had their fun, and were left with their tails tucked between their legs from the words of Mia, he looked to her, "You've got balls, Mia," He said to her, smiling. "I think I mis-judged you," He added, "Perhaps studying with you might be fun after all," He said, before taking a fork full of food into his mouth.