A heroic type of character might see the Sans fight as a great challenge. They would be eager to face him and prove their worth. They might respect Sans as a worthy opponent and try to fight him honorably.
Frisk could be one of the characters watching. Given their role in the game, they would be interested in Sans' fight as it could impact their journey through the Underground. Additionally, Undyne might be present. She's a strong fighter herself and would probably be sizing up Sans' techniques, maybe even learning from him or being critical of his fighting style depending on her mood.
There are quite a few, like bold, italic, and regular. Each gives a slightly different look and feel.
If it's a romantic fanfiction about him and Annabeth, he might blush a bit. After all, it's about his relationship. But he'd also be happy that people see their love as something worth writing about. If it's an action - packed fanfiction that has him on a new adventure, he'd be excited. He loves adventures, and seeing new ideas for his heroic deeds would be appealing to him.
Rainbow Dash might see humans as potential rivals in terms of physical abilities. She'd be eager to show off her flying skills and might challenge a human athlete to a friendly competition. And if the human showed some really cool skills, she might gain respect for them. Pinkie Pie, of course, would just be all over the humans. She'd throw parties for them, introduce them to all her friends, and make sure they had a great time in Equestria. She doesn't really care about differences; she just wants to have fun with everyone.
Well, if it's a comical Spider - Man fanfiction, Clint would be the first to laugh out loud. He has a good sense of humor and would enjoy the light - hearted take on Spider - Man. When it comes to dark and gritty fanfiction, Steve might be a bit concerned. He believes in the positive image of heroes, and such fanfiction could go against his ideals. Tony, however, might see it as an interesting exploration of the character's potential in different situations.
For the romantic fanfictions, Sirius would probably be all for it, especially if it involved some steamy relationships. He'd be like, 'Ooh, this is spicy!'. James might be a bit more reserved, especially if it involved his relationship with Lily in a way he didn't like. Remus would be interested in how the relationships were developed. In adventure - based fanfictions, Sirius and James would be excited, seeing new adventures in the wizarding world. Remus would focus on the logic and the world - building in those stories.
In the fanfiction, a character might also react with confusion. Sans' attacks and his overall fighting style can be very unique and hard to understand. A character who is used to more straightforward combat might be completely bewildered by Sans' moves, not knowing how to counter or even react properly.
If it's a action - packed fanfiction, Ruby would be all over it. Yang too, as they both love high - energy battles. Weiss might prefer a more refined, political intrigue - based Star Wars fanfiction where she can analyze the power plays. Blake would be interested in the darker, more morally ambiguous fanfiction that explores the grey areas of the Star Wars universe.
Yuno might be a bit more reserved in his reaction. He's more of a calm and collected character. He would carefully analyze the fanfiction, looking at how the writer has portrayed his growth and his relationship with Asta. If he finds something that doesn't match his own view of his character, he might be a little disappointed, but overall he'd be respectful of the creative effort.
There are protagonists, who are the main characters around which the story revolves. Then there are antagonists, who oppose the protagonists. There are also supporting characters that help to develop the story, like the sidekick of the hero. And flat characters, which are simple and one - dimensional, often serving a single purpose in the story.