It's possible that Tony wants to control the narrative. By protecting the fanfiction, he can ensure that the stories about his AIs are in line with his values and goals for the technology. Also, protecting fanfiction can attract more people to be interested in his AIs, as it shows a positive and inclusive attitude towards the fan community.
Well, it could mean that Tony is safeguarding the fan - made fictional stories about his AIs. Maybe he doesn't want them to be misused or plagiarized.
Negan might protect Carl out of a sense of respect. Carl has shown himself to be a strong and determined character, and Negan could admire those qualities.
It could be that the Tony fanfiction doesn't align with the team's vision or values. For example, if the team is trying to create a certain image or brand, and the fanfiction goes against that in some way, they would neglect it. Also, if the fanfiction has a lot of inaccuracies or goes too far from the original source material regarding Tony, the team might choose not to give it any attention.
He might just be a big fan of Loki himself in the fanfiction world. So, he wants to protect the stories that feature Loki.
One reason could be that Tony is trying to protect Peter. He might think that by being harsh and making Peter cry, he can keep Peter away from a dangerous situation. For instance, if there's a really tough mission coming up, Tony might push Peter away by being cruel so that Peter doesn't get involved.
One reason could be that he's on a mission to find other heroes in the universe. He believes that Earth needs more allies in case of future threats. So he leaves Earth to search for powerful beings or civilizations that could potentially help protect Earth. He embarks on this journey alone, relying on his Iron Man technology and his wits to survive the perils of space travel.
Lucius could have a change of heart due to Hermione's bravery. When he witnesses her standing up to the dark forces fearlessly, he might be reminded of the qualities he once admired in the wizarding world before getting involved with the dark side. So he decides to protect her to preserve that bit of goodness.
Maybe McGee lost his own clothes somehow. So he has no choice but to borrow Tony's clothes. It could be an accident like his luggage got lost or his clothes got ruined in an incident at work.
Some writers might want to explore dark and extreme scenarios. It's a way to break the norms of the usual heroic storylines. They may be interested in seeing how the characters and the Marvel universe would react to such a tragic event.
Percy Jackson might be in a position to protect Harry Potter fanfiction because he has experience with different mythologies and magic systems. He knows that fanfiction is a way for fans to explore and expand on existing stories. He doesn't want to see this creative outlet be silenced. His own journey of being a demigod in a world full of gods and monsters has taught him the importance of different perspectives. And Harry Potter fanfiction offers many different perspectives. So he uses his powers and influence to safeguard it.