BFSpinel lore-dumpin time! (And sorry for the quality, my phone camera's not that good)
Way before joining the Crystal Gems, BFSpinel used to live at the Mickey Mouse Clubhouse (what a crossover mess, I know), alongside Mickey, Minnie, Donald, Goofy, Daisy, and BFSpinel's best pal (at that time), Toodles!
They used to have kinda childish, but fun, calm and silly adventures, like that time Pete said the wrong magic words, making the Clubhouse fall apart in several pieces and flew away ("Mickey's Great Clubhouse Hunt"), that other time they formed a band called "The Sensational Seven" (My AU version of "The Sensational Six") ("Mickey's Big Band Concert") (fun fact: this is where BFSpinel got his taste for music), that one time Donald broke a coo-coo clock he was gonna gift to Daisy, and thus, that coo-coo bird flew away, making Mickey, Donald and BFSpinel fall into Wonderland ("Mickey's Adventures in Wonderland"), along many, many other ones...
Everything stood like this.... until one day, BFSpinel has decided it was time to start a new chapter on his life, calling his last adventure at the Clubhouse "A Goofy Fairy Tale" (Clubhouse finale btw), he packed everything he needed on his backpack, said goodbye to Mickey and friends, and he left, going to the open road, ready for whatever the future had for him, not knowing he will join a certain Gem team later on...