There's also a chance he meets some of the other early Avengers or their predecessors. He could form new alliances or give them advice that would change the course of their heroics. For instance, he could meet the Howling Commandos again and lead them in a new mission that has a big impact on the future of the world.
He could meet Peggy Carter. Since he had a strong connection with her in the past, it would be a very emotional reunion. They might share some unspoken feelings that were left unexpressed before.
He could also meet Odin. Odin might view Captain America as an interesting mortal from Midgard and might have some words of wisdom or a task for him to complete during his stay in Asgard.
In this fanfiction, he could also meet his past self. It would be an interesting encounter. They might have a conversation about his future experiences and how to better protect the world. And he may use his knowledge of the future to train his past self, making him an even better hero.
He could meet Dr. Halsey when she was just starting her research on the Spartan program. Master Chief could give her some insights from the future, which might change the way the program is developed.
She could meet her younger self. This would be an interesting encounter as she could offer advice and guidance to her younger version. Maybe she could help her younger self to be less afraid of her powers.
He could meet his past self. It would be really interesting to see how he interacts with his younger, more naive self. He might try to give advice to his past self, like how to better control his power or avoid certain dangerous situations.
She could also encounter characters who were once enemies but are now in a different situation due to the time travel. For instance, she might come across a young Death Eater who hasn't fully committed to the dark side yet. Ginny could try to change their path and prevent them from becoming evil in the future.
He could meet his past allies in a different context. For instance, he might encounter Kakyoin or Polnareff when they were just starting their journey. Maybe he could also run into Dio at a time when Dio was still plotting his rise to power, which would create a very tense situation.
Lucy may also come across ancient warriors. For example, she could meet a Spartan soldier and be amazed by his combat skills and strict discipline. They could have a brief encounter where the Spartan is curious about this strange girl from another time.
There's a possibility that Zuko would meet his grandfather. His grandfather's actions and decisions might have influenced the path the Fire Nation took towards war. By meeting him, Zuko could try to sway his grandfather's views and change the future of the Fire Nation at its root.
Qrow might meet the founders of the Huntsman academies. He could learn from them the original intentions and philosophies behind the creation of Huntsmen. He could also offer his own insights based on his experiences in the future. This interaction could lead to significant changes in the way the academies are run and the training of Huntsmen in the past, which would then have a ripple effect on the future.