A third storyline could be a mystery - based one. There could be some sort of mystery surrounding an old dance routine that Michael and Tatiana once worked on together. As they reunite years later, they start to dig into the past and uncover secrets about the dance, its origin, and the hidden meanings behind it. This could involve some old rivals trying to stop them from finding out the truth.
Another storyline could be a time - travel fanfiction. Imagine Tatiana going back in time to the early days of Michael's career and being able to change some small things that had a big impact on his later life. Or perhaps Michael traveling to a future where he sees the long - lasting impact of his music, with Tatiana by his side as a witness to his legacy.