Earthly Secrets

When the 100 fell from the Ark, there was girl that would change things. Bellamy didn't get on the Drop Ship for Octavia. He got on it for Sorcha, a girl that he had fallen for.
What he doesn't know is why Sorcha is on the Drop Ship in the first place.
Bellamy and Sorcha were best friends, and shared a few kisses before she was locked up. And Bellamy didn't want her down there without him. He knew how she managed in stress, and knew how she would handle it.
What's if he's wrong? What if she changed in the year that she spent in the Sky Box? What happens when he finds out how she got there in the first place?
And most of all, what happens when she takes control over his group, and all of the 100?