Well, if 'Based on a True Story' is a project in the entertainment field, Brandon Keener could be one of the many elements contributing to it. He could be an artist involved in the creation, perhaps an actor who brings a particular character to life. But again, without more details about this 'true story' - based project, it's difficult to give a more in - depth account of who he is in relation to it.
Alexis might confront Beckett directly. She could say something like 'I think you're cheating on me. What's going on?' This is a very straightforward approach.
I don't know who Alexis is in this story without reading it. But it's likely that Alexis is either the main character or an important figure in the events that unfold in the 'creepy subway' setting.
The significance of Brandon Keener in 'Based on a True Story' is unknown without additional information. He could be important for the plot, but we need more details to tell.
Harley Keener does not become Iron Man in the comic universe. The storylines and character developments don't lead in that direction. He might have his own unique adventures and contributions within the comic world, but not as Iron Man.
A lawyer could be an important character. This lawyer takes on Alexis's case, believing in their innocence. The lawyer has to battle a corrupt legal system or powerful opponents who want to see Alexis locked up for good. The fanfic could show the lawyer's strategies and how they build a case in Alexis's favor.