Riley and Tweets instantly chose eachother. But that is the exception to the rule. Jessie pestered the daylights out of Samson for months before Samson would let Jessie perch next to him. They eventually became best friends. Rainbow and Solomon are cage mates because the flock is so much smaller.

I remember Noelle the lovebird couldn't stand Niholas the lovebird. They both ended up hanging out wiht budgies rather than eacother.