In my opinion, Sirius Black would be really interesting. He could use his Animagus form to his advantage in Skyrim, maybe scouting out areas or sneaking past enemies. The witches and wizards from the Harry Potter world could also interact with the various races in Skyrim, like the Khajiit and the Argonians. And imagine Snape in Skyrim. His potions knowledge could be useful, and his brooding personality would contrast with the more rough - and - tumble characters in Skyrim.
Definitely Dumbledore. His wisdom and powerful magic would be fascinating in the Skyrim setting. He could interact with the Greybeards and learn about their way of life. Harry himself would also be interesting as he could use his Gryffindor courage to face the challenges in Skyrim, like the dragons. And Hagrid would be great too. He could bond with the giants in Skyrim.
I think Hermione would be a great character to include. Her thirst for knowledge would lead her to study the different magics in Skyrim. She could befriend the mages in Skyrim and exchange knowledge. Also, Voldemort could be an interesting addition. His dark magic could cause a stir in Skyrim, and perhaps he would try to take over the land. And the Dragonborn from Skyrim could also be included. They could team up with Harry and his friends to fight against common enemies.
For the PJO side, Nico di Angelo could be a great character. His control over the dead could have some really strange and interesting interactions in Skyrim, where there are also undead creatures. On the Skyrim side, Ulfric Stormcloak or Elisif the Fair could be included. Elisif's leadership and Ulfric's military might could be factors when dealing with the demigods. If the demigods get involved in the civil war in Skyrim, their powers could completely change the balance of power. And Luke Castellan from PJO could also be an interesting character to bring in, as his complex personality could add a lot of drama to the crossover story.
Definitely Naruto himself. His energetic and determined personality would be a great contrast to the often more somber characters in Skyrim. Also, characters like Sasuke could be interesting. His brooding nature and powerful Sharingan abilities would make for some great interactions in Skyrim's dangerous world. And from Skyrim, the Dragonborn would be a must - include. The clash or cooperation between the Dragonborn's Thu'um and Naruto's jutsu would be really exciting to write about.
The Master Chief is an obvious choice. His stoic and powerful presence would be really interesting in the Skyrim setting. He could be like an otherworldly hero, and his Spartan abilities would make him a force to be reckoned with against Skyrim's foes.
Definitely Harry Potter himself. His courage and magical abilities would make him a key figure in any adventure involving the fleet of Fod. Hermione would also be great as she could study and figure out the Fodian magic related to the fleet. And Hagrid, because his love for magical creatures might help in dealing with any strange beasts associated with the fleet.
The Dragonborn would be an amazing crossover character. Imagine the Dragonborn showing up at Hogwarts. They could use their Thu'um in the hallowed halls of the school, which would surely cause a stir. The Dragonborn's ability to absorb dragon souls and their combat skills would make them a force to be reckoned with in the wizarding world. They could also learn about the different types of magic in the Harry Potter universe and perhaps use it to enhance their own powers.
Leonidas from '300' would be a great character to focus on. Imagine his reaction to the magic of the Harry Potter world. He's a fearless leader, and seeing him interact with wizards and magical creatures would be fascinating. He might see the magic as a new weapon or a strange form of sorcery that he has to either embrace or fight against.
The Joker could be an unexpected but exciting addition to this crossover. Imagine the chaos he could cause in the wizarding world. His madness and unpredictability would be a huge challenge for the wizards and witches. And Batman would have to find a way to stop him in a world full of magic, which he is not used to. Also, Snape's complex personality could add more depth to the story when interacting with Batman.
Definitely Hermione. She's so smart and curious that she'd be all over Naruto's abilities. She might even try to write a book about it. And then there's Sirius Black. He could be like a cool uncle figure to Naruto. In Naruto's world, Jiraiya would be a must - include. He could have a great time exploring the wizarding world and flirting with witches. He might also teach Harry some of his unique ninja skills.
Definitely Harry Potter himself. His unique magical abilities and his sense of justice would make him a very interesting character in the world of Westeros. Also, characters like Dumbledore could be interesting if they were somehow brought into the story. In Westeros, characters like Tyrion Lannister could have some really interesting interactions with Harry. Tyrion's wit and political acumen combined with Harry's magic would make for some great scenes.
Definitely Harry Potter himself. His character is full of depth and his magical abilities would make him stand out in Westeros. Also, characters like Tyrion Lannister could be interesting. His sharp wit and political acumen combined with Harry's magic could create some really engaging storylines.