Even a non-bonded pair but know each other can be successful. One of the SPCA fosterers I used to know had many many foster cats in her care and even those who weren't really a 'pair' did well together. Last summer, I also found a home for two stray kitties hanging around here and while they weren't buddies (two adult males), they are amazingly bonded now. It only took a short separation period and now they are inseparable.
