Lucien Enjolras

"Obviously Bro Code is you don't sleep with your bro's love interest," Magnus says, wisely. "That's never an issue for me, of course, because I'm deeply committed to Alex, but I still abide by it on principle, you know? Best Friend code is you form honest but supportive opinions on the people your best friends love. Other Best Friend Code is you hear your best friends out and give their arguments full consideration even if you disagree with them -- it's a respect thing. And Girl Code," here he makes direct eye contact with Lancelot, "is that if your friends are softening towards someone who could be bad news for them, or whatever, you support you friend but also hate the guy for them, so they don't have to but there's still someone keeping an eye out."