I take it it's slightly AU crossover since William and John are still alive?

Yeah, I have no idea why they were there. But Charles and Haytham were probably stunned by how they were still alive and interacting with Connor. Though I do wonder if MotH!Charles would be jealous of his other-self.

I hope I'm not depressing you anon!

Of course not! It was just one of those dreams I wish did not end... and one I wish I could write /stares at long list of uncompleted fills/