Actually when it comes to male mice,they are highly territorial and will fight to the death in many cases.Introducing a new male to Fedex will most likely prove to be a disaster! Fedex will do fine on his own,as long as you give him alot of attention and toys and things to do.Cute Mousie! I'd like to let you know that mice don't do too well by theirselves! They're very social animals, so you really should try to find him a friend! If Fedex is a boy, be sure to get another boy!!! But try to get a young one as male mice can be territorial! Check out some sites to see what all is best! There's a lot of info out there so just Google it! =) Good luck with your new little friend!