Hi, welcome to Just Answer, I will try to help answer your questions. Have you talked to your friend in jail? Does he know you are caring for the cat?
It looks like you are offline at the moment. I'm going to leave some information here and switch to the Q&A format to make it easier to reply to you later as well.Legally, the cat belongs to your friend, and as much as this cat obviously loves you and you love him, ultimately your friend has legal ownership and will be allowed to take him back. I think you may want to let your friend know how you feel, how much you have become attached to Mem, and let him know you would like to keep the cat. You may even offer to buy him a new Bengal to replace this one. If your friend is insistent on taking his cat back, keep in mind that he probably loves him as much as you do and will be heartbroken without him. You might consider finding out where your friend got Mem, and contacting the breeder to get your own Bengal from the same line. I know it's not the same as keeping Mem, but might be your only option.Good luck, I hope it all works out for you and your friend, and especially Mem.