Anakin could encounter future versions of his friends or enemies from the past. For instance, he could run into a future version of Obi - Wan Kenobi who has also somehow traveled to that future time. Or perhaps he meets a new generation of Sith who have different motives and methods compared to the Sith he knew in his own time. They could challenge his understanding of the dark side and the Force in general.
One idea could be that Anakin travels to a future where the Jedi Order has been rebuilt in a new and unexpected way. He might initially be confused by the different teachings and practices. For example, the new Jedi might have a more inclusive approach, accepting Force - users from all walks of life, not just those trained from a young age as in his time. This could lead to Anakin having to re - evaluate his own understanding of the Force and his place in the Jedi legacy.
Obviously, he would interact with his younger self. He could try to guide his younger self, offer advice on how to control the Force better and how to deal with the temptations of the Dark Side.
There could be a hermit or an outcast Jedi or Sith on Dathomir. Anakin meeting this character could lead to a great revelation. Maybe this character has been in hiding on Dathomir for years, observing the balance of the Force there, and Anakin's arrival disrupts that balance and forces an interaction that changes Anakin's perspective on many things.
Well, he might be shocked by the advanced technology. Maybe he'll see flying cars and buildings that touch the sky. He could also encounter new forms of the Force that he doesn't understand. And perhaps he'll meet descendants of his friends or foes, which would be really interesting.
He might start by observing. Aang is a curious person, so he'd likely watch how people live, how they interact with technology. He may also try to find other benders to learn about any new developments in bending. And he'd probably use his kind heart to make friends easily in this new future environment.
Perhaps he discovers that his actions in the past had far - reaching consequences that he never anticipated. In this future, the galaxy is on the brink of a new kind of disaster because of the events he set in motion as Darth Vader. He then has to figure out a way to correct the course of history, even though it's a future he's in.
In this fanfiction, Harry might see a world where magic has evolved in ways he couldn't imagine. Maybe there are new spells and potions that are far more advanced. He could also encounter the future versions of his friends and enemies. For example, he might find out that Ron has become a very important figure in the wizarding world, or that Voldemort's influence still lingers in some unexpected ways.
Maybe Hamilton would see a future where the ideals he fought for have been fully realized. He might be amazed at the technological advancements and how they have been used to uphold equality and freedom.