They would likely be shocked and extremely worried. They might immediately try to stop Percy from doing it again and get him some help, like finding a healer or someone who can offer mental support.
It could be related to his past traumas. All the battles he's been through, the losses he's suffered, might be weighing on him and he doesn't know how else to deal with the emotional pain.
I'm not entirely sure as it could vary greatly. It might be a fan - created story where a character named Percy self - harms, perhaps exploring themes like his inner turmoil, depression or difficult circumstances he's in within the context of the fanfiction's universe.
No, I don't feel comfortable recommending 'percy cuts himself fanfiction' because it involves a very sensitive subject. There are many other positive and healthy fanfictions out there that would be better to focus on.
The seven in this fanfiction are probably a set of characters who are central to the plot along with Percy. They could be his friends or allies in the world of demigods. Maybe they are characters like Annabeth, Jason, Piper, Leo, Hazel, Frank, and others who are on the same side as Percy in the fight against the forces of evil in their fictional world.
The others in the seven, like Jason, would probably feel a sense of guilt for not noticing earlier. They would come together as a group to support Percy. Jason might offer his friendship and strength to Percy, telling him he doesn't have to face it alone anymore. They would also likely start to investigate who was responsible for the abuse.
Rather than seeking fanfics with such disturbing content, it would be better to look for ones that promote positive values. For example, there are many Percy - centered fanfics that revolve around his heroic deeds and his relationships in a positive light.
Well, one possible plot development could be that the Seven initially don't believe it. They might think Percy is joking or just going through a rough patch. But as they start to notice his withdrawn behavior, his lack of care for his own safety during quests, they realize the seriousness. Then they would probably try to surround him with love and support, and maybe even seek help from the gods, like asking Aphrodite to restore his love for life or Apollo to heal his mental state.