See my vision: Breanna as the secret time-traveling daughter from the future of Hardison and Parker.
You know all those comic plot lines where the teenage/young adult child of the main character(s) time travels back and meets their parents before they are born? Basically that, where Breanna is that trope and she travels back and ends up working with her parent's old crew before she was born while in secret she works to repair the time travel technology so she can get back.
Maybe it's an AU and she wasn't with Nana for as long and only got there when she was 17/18 but needed someplace she could trust and she knew where Nana would be (moved around a lot less than her parents and had reason to take in a lone teenager without having to reveal time travel stuff) and it's gonna take a few years but she will get back. Or maybe it's not an AU and something went really wrong with the future and she has been at Nana's since she was 11/12 because she was sent back to escape a terrible fate and she wants to do everything she can to prevent it. And she's worried about upsetting space-time, or preventing her own birth.
(I personally don't see Parker getting pregnant intentionally, but just maybe, if things were super, super chaotic, maybe including getting stranded on a desert island or something for a bit, I could see her somehow not figuring out exactly what was going on until after like 23 weeks).
But then it starts to get closer to Breanna's birth, and she has seen Doctor Who, has seen the episode "Father's Day" where when Rose holds herself as a baby, it creates a paradox and calls a time reaper into the room with them. Breanna would very much like to NOT be attacked by time reapers. (whether or not this is actually how time travel works here doesn't matter so much when Bre considers it a distinct possibility and is working off that fear). So she frantically starts trying to hasten her time machine fixing, but the others figure out something is wrong, there's some sort of catalyst, and she eventually comes clean to them.
She has to go back, and they help her finish the machine fixes and get there. She says goodbye and she is going to miss them but she's just going back to older versions of them. They're going to miss her, but they realize they will meet her again (for the very first time) quite soon.
Anyway, I just think it could be a cool concept to play around with.















