3. Susan
After The Dalek Invasion of Earth, we leave Susan behind on 22nd century Earth with her new boyfriend. I envision picking up right where we left off, with Susan struggling to restore post-apocalyptic London to its former glory, all while navigating through her first relationship and grieving the loss of her beloved grandfather. It's a gritty, stark drama, more Walking Dead than Star Trek. As one of the leaders of the new society, she must deal with dissension in the ranks, as they squabble over how to rebuild while fending off opportunistic alien invasions. Also, in an increasingly xenophobic atmosphere, Susan must keep her identity as a Gallifreyan a secret, or risk losing everything. I'd be particularly keen to see something like this, because Susan didn't exactly get the best treatment during her time on the show. Aside from An Unearthly Child, The Dalek Invasion of Earth, and arguably The Sensorites, the writers didn't exactly know what to do with her. So they decided the best thing would be to have her whine and twist her ankle a lot. This would be a chance to redeem her, to show the world the potential that Susan always had to be a really great character.