Our 2 are an interesting pair.
They are both BL foster birds, but that's where the resemblance ends. Charlie came to us first. He was originally parent-reared and probably aviary but had been living as a companion bird for about 10 years before he came to BL. Consequently he wasn't really companion or aviary. He didn't really vocalise much when he came to us (only occasional squeaks). A lot of time and patience allowed him to become more relaxed, but he didn't really know how to 'be a bird' (he was incredibly neat and tidy, apart from his plucked chest.)
The BL Directors suggested taking on another Grey as a companion for Charlie - hence Joey arrived. He is a hand-reared companion bird (his Mummy's baby) who is naughty and messy, just as a bird should be

! He taught Charlie how to sing (Charlie makes up his own tunes now, although still doesn't know words), whilst Joey nattered his favourite phrases all day long. He taught Charlie that he could trust us and most of all, he taught him to enjoy life. They do enjoy each other's company, although there are times when Charlie needs a break from Joey (who seems to act like his daft younger brother.) They do sometimes feed each other, but not very often. They seem to look out for each other though. (Charlie does get really annoyed when the naughty and greedy Joey pinches food from his bowl.
So, in short, they spend all day out of their cages together on their playstand, but Charlie sometimes takes himself onto the Java tree for a break. (Joey, who is clumsy. is scared of climbing the tree.) They both sleep in separate cages, as I suspect that Joey would pester Charlie all night and he would never get any sleep. They both love their routine though.
When we need someone to look after our boys, they go to Shaz (who is a BL member and a Grey specialist.) Having spent time with her flock, I suspect our 2 would be happy without each other's company, provided they had acceptable company instead. (I hope that makes sense.)
Incidentally, I don't know if you're aware, if you take on a BL bird that bonds with your own, those birds should remain together for the rest of their life (even if that means giving up your own bird with the BL bird.)