Good evening. I am hoping someone here can help us. We have two cats, a 4 year old male, Max and a 2 year old female, Maia. Both were adopted from agencies and their relationship took off immediately. My boy became maternal to our little girl and they do everything together. A couple of weeks ago we were adopted by a stray who had been very friendly with us. I collected him, took him to the vet, had him tested, neutered, and shots were given. My little boy Max is an angel, never a hiss or growl, rarely even meows. As I write this he is asleep on my lap so contentedly. The stray, whom we named Meeko, is highly aggressive to Max. However he is very loving towards us. I have never seen cats fight like this. He had puncture marks in his hips and tail where Meeko managed to get a hold of him. I've tried everything I can find online about introducing them, but none of it seems to work. Meeko has his own room that he stays in most the day, only wandering when the others are asleep and closed in their/our bedroom. The couple of times he has come into contact with Max he has torn him apart. He has never bothered Maia. Both kids are scared of him. I hope for this to get better. I came into this knowing that they may not be compatible. I guess I'm looking for advice on something else I might try, or how long I should continue before giving into the notion that he is causing more harm than good and adopting him out. Any help would be welcome. Thank you for your time.