Finn and Ben fit together.
Finn, a war hero and a Senator for the stormtroopers settled on Kef Bir, experiences an assassination attempt. The Senate, furious at Finn for insisting on stormtroopers' right to self-determination, assigns him a convict who's had his ability to access the Force stolen from him: Kylo Ren.
Then shit really starts getting weird.
When Finn and Kylo meet again, the world is falling down around them.
Kylo lies about Finn being his boyfriend. It only gets more complicated from there.
Finn just wants to keep his head down and prove himself in the Resistance. Unfortunately for him, he also has to deal with Kylo Ren haunting his strangely realistic dreams, accidentally getting General Organa as a teacher, and a spreading stormtrooper rebellion.