Another possibility is that he meets some sort of time - keeper or guardian of the future. This character could be guiding him through the mission, or perhaps trying to stop him if they think his presence in 2110 is a threat to the natural order of time.
There could be new types of magical creatures that have evolved or been discovered by 2110. Harry might interact with them, and they could either help or hinder his mission.
Obviously, he could meet Darth Vader. Their encounter would be really interesting as they are from two very different fictional universes. He might also come across Luke Skywalker. They could form an alliance, with Harry sharing his knowledge of magic and Luke sharing his skills with the Force. Another character could be Han Solo. Harry would be amazed by Han's piloting skills and Han would be intrigued by Harry's magic.
Perhaps he'll meet an old patient who has been in the hospital for a long time. This patient could tell Harry some long - forgotten stories about Hogwarts in the past. There could also be a chance that he meets some other students who are also in the hospital for various reasons, and they might form a new friendship or alliance.
Perhaps he'll meet some interesting magical creatures that are native to the holiday location. It could be a friendly forest sprite or a wise old centaur. He may also cross paths with some international wizards who are also vacationing there and learn about different magical cultures from them.
He could meet the castle guards. They might be suspicious of him at first but then become friendly as they realize he has no bad intentions.
He might meet the house - elves that have been taking care of Potter Manor for generations. They could show him around the manor and tell him stories about his family.
He might meet American witches and wizards. Maybe a young and adventurous wizard who shows him around the American magical world.
He could meet new professors who have unique teaching methods and vast knowledge of different magics.
He could meet Bella. Since Forks is Bella's hometown in the 'Twilight' series. They might become friends or have some kind of adventure together.
Well, it could be that Harry is sent to a future time in 2110 for a top - secret mission. Maybe he has to deal with some advanced technology that he doesn't understand at first. He might encounter new forms of magic or threats that are unique to that time period.
He might meet Hermione. Since Hermione is always interested in academic things like Owls, she could be there to help Harry or just be involved in some research related to it.