That would be the glory of a PvP server, He doesn't have to give your stuff back. He isn't allowed to harass you, by killing you over and over again. He cant kill you and steal from your chests or grief your house (In Normal World). However, he can kill you and take whatever you drop, Its a rule, Try reading them

CHILL YOUR BALLS, MAN

make me ass hole, you/your friend wont be refunded! i lost over a stack of gold bars (if i were to make diamond armour and swords and such) to the pain in the ass "karterchamp" was i bitchin? yeah, then i got over it! oh and heres a saying, cry me a river and get over it!"

You need to learn when to stop. Someone lock before we all end up looking like asshats