He might not have been socialized well with his last owners. Define mean? is it just striking or does he mostly do hissing? If hes hissing just hold him anyways. Ball pythons are super head shy. So that would explain why he freaked out a bit. Though thats a pretty big freak out lol. The time that there most likely to bite you is when your picking them up from the cage. Now it might leave a mark but it doesnt hurt very much. Also are his eyes a funny color? If its a creamy blueish color it could be retained eye caps, and that could cause him to freak out a bit more with his head. Just be patient with him. Handle him even when he is being a *****. And eventually he should calm down. My first ball python hissed at me every time i got him from his cage. Which scared me at first b/c he was my first snake. But i learned that he was all talk and know play so i held him anyways. and one day as if over night he just stopped hissing. After that he was pretty good about being held. So just keep trying to handle him even if he trys to bite you or hiss's and eventually he should get more use to handling him. Let me know it goes!