Legends will bring closure to its central mystery at the end of Season 2, showrunner Ken Biller revealed in an interview with THR:
One thing that I wanted to do this season that I thought I really owed the audience is that question of “Who is Martin Odum?” Identity is the main theme of the show. If the audience watches season two of Legends, when they get to the last episode, they will be told who Martin Odum really is. I thought it was important to not just keep teasing the audience and give them the real answers. The reward for the audience of just paying attention and sticking with it is they’re going to get a lot of answers.
With a third season far from guaranteed at this early stage, Legends could be perceived as preparing for the end, or at least taking precautions in the event of cancellation.
That said, it’s also possible the ‘big answers’ will lead to even bigger questions to be explored in Season 3, should the renewal gods be so kind. Watch this space…