Basically a rewrite of the Rear Axle episode and most definitely inspired by the fact that Hailee Steinfield makes music.
Bee and Charlie were sparkbonded before TF Prime. It was on accident and on a whim since the two immediately never saw each other again after the bond. When Team Bee arrives on Earth, Bee believed she already died of old age unaware that the spark bond stops humans from aging.
For the entirety of Prime and RiD, Charlie was stuck at 30-years old.
Charlie thinks that Bee is still on Cybertron and lived out different lives since he left. She was a military assassin, a NASCAR racer, a ballet dancer, an actor, a writer, and Olympic Diver and Archer.
Currently she’s CHARLOTTE, a pop star who’s performing with Rear Axle to debut their latest song they made together. Russell is a huge fan of her and willingly goes. Bee thinks that CHARLOTTE could be related to Charlie but doesn't want to give himself hope.
When he is accidentally on stage, Bee is starstruck by Rear Axle then Charlie goes on stage and the two immediately recognize each other and dance with each other on the stage, happy to be reunited after so long.
The two stayed in touch while Charlie was on tour, Bee insisting her to stay away until the all the escaped Decepticons were captured. After the Autobot High Council was formed and Team Bee decide to stay on Earth, Charlie stops making up new lives and returned to Bee's side to renew their vows.