Avengers: After the Endgame

"It can't be undone." Clint Barton's words. The entire Avengers accepted the fact that there is no way to bring Natasha or anyone back when the truth is, THEY HAVE A TIME MACHINE!!! What would happen if they'd use that to bring Natasha, Tony, Vision, and Loki back?
The Avengers are facing new and old threats. But what they don't know, is that the world is a whole lot bigger than they thought. Two girls who argue all the time, a movie-loving superhero fan, and a new friend with mindpowers changes everything.

I'm planning on mostly Avengers, but it will contain Agents of SHIELD, Arrowverse (Flash, Legends of Tomorrow, Supergirl, Batwoman, Arrow), and Avengers Assemble.