Hi everybody, I hope somebody can please help with our dilemma. We've recently got a new male cat (Reg) around eighteen months old to add to our female cat (aggie) who is about 6 years old and formerly a stray. The new cat was neutered about 5-6 weeks ago by the cats protection league from where we got him and we've had him for about two and half weeks now. He is being kept in a room, until he has settled down, from which he is obviously desperate to get out of with lots of meowing and scratching. That's understandable but on the few occasions we have let him out and tried to introduce the cats to each other Reg has been absolutely obsessed with intimidating Aggie and invading her space and in the few cases where we have been unable to intervene has attacked her. It's all he wants to do when they're together. This has left Aggie very shaken up. She is usually quite assertive but is very scared of the new cat and wouldn't come back in last night after a particularly bad altercation. We have bought some pheromone diffuser which has been in his room for about a week maybe but to no effect as yet. The strange part is that he is an incredibly affectionate cat around us but this aggressive streak is too much and we really don't want to send him back so any advice would be much appreciated. Thank you.