An AU in which Twilight goes the Tempest path, Tempest goes Sunset's and Sunset goes Twilight's

1) Twilight gets her horn broken by an ursa major/minor and get abandoned by her friends (implied mane 6 as kids) and then runs away from her home
2) Spike's egg never gets found by Celestia. Instead, his mother's cave was raided by Diamond Dogs who seeked to claim all the gems. His mother was defeated in the process, and Spike hatched. Diamond Dogs decided to "adopt" him to use his dragon abilities for gem search and digging, making him their — ironically — "dog"-pet (hence the name)
3) Giant collar on his neck also keeps him from growing into a big dragon via greed
4) Twilight accidentally "frees" him by defeating Diamond Dogs when they tried to take her gem currency. Spike thus became her "pet" instead and they just kinda both rolled with it since they have no one else
5) Eventually Twilight becomes a good guy and even an alicorn, though instead of just regrowing her horn, her broken horn grows a crystal-like sparkly full form, and she grows a pair of glowy wings. I'm still thinking about their design, so this is a WIP, ofc
6) They become very close friends, almost a family, or perhaps, almost romantic partners. It's not certain yet