So I definitely think Zack meets Cloud first and drags him to the rest of the Firsts and they just all grow really endeared to him. They likely thought he was just another of Zack's friends, to anxious and shy to ever get along with the group, but he eventually mouths off at Genesis or Sephiroth and theyre like oh... this kid is good. Genesis loves the way Cloud is enthusiastic about Loveless (its not like he could have read it before out in Nibelheim) Angeal adores the way Cloud takes interest in his plants, and although I feel like Sephiroth takes the longest to come around, he eventually finds a lot of common ground with their love for personal space and tendency to run from problems, lmao.

I think Angeal and Genesis are always the first to get together in AGSZC, but I don't think it means they prefer being with each other preferred to anyone else. I do, however, think they balance each other very well. I like to imagine Cloud can get very self conscious and shy and A & G have the perfect ratio of calm and crazy to pull him out of his shell. Oh, I do think they're both huge teases though, and together they can entertain themselves and drag sex out so long that Cloud is sobbing while begging them to stop edging him... I should write a oneshot of that. Mwah.