Stiles looked like he wanted to fight with Derek but the teacher assistant could be just as stubborn as Stiles could be. Plus Stiles knew Derek was right. Derek was a teacher and should be out there patrolling the halls and making sure all the students are safe.
“You’re sick,” Stiles argued and he summoned another glass of juice and held it out to Derek. “It would explain your lack of an appetite at supper. Drink this. If you’re going to be stupid and wear yourself out you should at least keep hydrated. And take Batman with you.”