How might Susan return?

The Doctor's granddaughter has been teased on screen throughout this recent season, fan theories abound and original actor Carole Ann Ford has stated she'd be happy to reappear on the show.

Let's assume that there is a reunion with Susan coming up; that would be exciting in itself, but narratively, how do you think it will be set up? Does the Doctor seek her out or will Susan find her grandfather first?

More to the point, "the Doctor finally sees Susan again" is just a story beat — how do you imagine the larger science fantasy story context surrounding it? Feel free to fanfic an entire episode plot or season arc if you want 🙂