Strangers to Lovers/We Had to Get Married AU aka "The Tepid Alliance AU"
In order to secure peace between the Autobots and the Decpticons and focus their efforts against an ongoing Quintesson invasion, Bumblebee and Breakdown have to get married. At first they are complete strangers, Bumblebee is the eldest and most formidable son to Optimus while Breakdown is Megatron's most disposable.
Breakdown lived his whole life as a "leftover" and was nervous, yet excited when Megatron selected him to be the Decepticon's new face. Megatron didn't expect this alliance to last and could spare him. Trained in diplomacy, music, and all around pleasantries, Breakdown thought he was the best choice, until he ended up sparked and realized exactly how bananas the Autobots are.
Bumblebee had no interest in getting married, in fact he didn't speak to his new Conjunx until well into his carrying cycle. "How'd he get sparked then?" I hear you ask. Bumblebee reached into his spark chamber, took a little pinch out and flicked it at him. Bumblebee lived a life of constant strife and by Optimus' side, to be removed from the action and placed with his former enemy was annoying to put it mildly.
Ironically it was Cliffjumper and Rodimus' constant teasing of Breakdown and their sparkling that caused Bumblebee to finally snap. At first Bumblebee did not care for the sparkling, it was a fact of being next in line for Prime, a heir was secured. But as time goes on, Piston grows on him and Breakdown is adamant to teach the baby joy. They all learn alot from each other, Breakdown learns to stand up for himself and not be a door mat, Bumblebee learns how to relax, and Piston learns how to dance.
This is for @breakbeeweek Day 4: Sweet/Sour