Jace-He teaches you how to throw knives, and you teach him how to not go on about himself when you need to make a good impression on someone
Simon-He teaches you video games, and you teach him about the Downworld and Downworlders
Raphael-He teaches you how to use your vampire powers (that mind control thingy that Simon used on his Mum, forgot the name, super speeding around without tripping on things, ect), and you teach him the basics of fangirls and fanboys, you know, that sorta thing
Jordan-He tells you about what's happening in Praetor, and that's about it, but, you constantly teach him about history, and how to stand in the same room as your crazy adopted sister without getting covered in glitter
This could have been better, but I wanted to give you guys an update, so it sucks, sorrrrrrrrrrryyyyyyyy