Like the others say, it will take time for Olive to accept newcomer Oscar fully. Though it is much easier to introduce a male to a female, rather than female to female. FACT!!!! So hope that helps. Olive will eventually mother him, and groom him. I have four cats, all aquired at different times and ALL took time to adjust to each other. Though male cats are far more laid back and accepting than the females. Don't wory, they will eventually become firm friends, though there ALWAYS be the odd fight and hiss/fallout, just like us humans! We fall out from time to time and so do cats, but the love for each other will still be there.