u/AdPhysical2118

hi! we brought home a new cat, male, 10 months old, yesterday and he is intimidating my 3 year old female resident cat. he is doing most of the hissing she she seems scared of him. we have the new cat in his own room and we have a playpen we have used to provide visual contact. when they are separate, the new cat is not scared and is extremely affectionate. is there any reason this is happening? what can we do to solve this? thanks for the help!