One common plotline is Ichigo trying to get his powers back. He might embark on a quest, perhaps traveling to some hidden or dangerous places. Another is that he discovers new latent abilities within himself that he didn't know about before his power loss.
Well, in many fanfics, when Ichigo loses his powers, he often has to start from scratch. He might go through a period of self - discovery. Maybe he tries to find new ways to protect his friends without his Shinigami powers. He could get involved in more human - related affairs, like using his martial arts skills or his intelligence in a different way.
A powerful sorcerer could be the main antagonist. Maybe the sorcerer is trying to gather all the meta - human powers for some dark ritual. He targets Beast Boy first because his power of transformation is unique and could be a key component in the ritual. So, he casts a spell that takes away Beast Boy's powers.
Maybe in the fanfic, there's a powerful villain who has a device that can nullify superpowers. Beast Boy gets caught in the range of this device and loses his powers. He struggles with feelings of uselessness at first. But then he realizes that his skills as a strategist and his knowledge of the Titans' operations are still valuable, and he uses those to help the team in a different way while also searching for a power restoration method.
His physical strength might increase. Thor is known for his great strength, and as his adopted son, Percy could inherit some of that. He might be able to lift heavier objects or fight more powerfully in close - combat situations. Maybe he could even hold Mjolnir for a short period of time, which would be a huge boost to his powers and status in both the Greek and Asgardian worlds.
It's possible that his powers could even be enhanced in some ways. Losing an eye could make him more in tune with his other senses, and this could translate to his powers. For instance, his ability to sense danger through water vibrations could become sharper as he has to rely more on it. His powers might also develop in new directions. Maybe he could start to use water to create illusions to compensate for his lost vision in battle, like using water to project false images of himself to confuse his enemies.
Naruto's chakra powers and Thor's godly powers could combine in interesting ways. For example, Naruto could use his chakra to enhance Thor's lightning attacks. Maybe when Thor throws Mjolnir, Naruto could add his own chakra boost to make it even more powerful and faster.
Thor may also find it amusing in a way. He's from a different world with different problems, and a human losing their glasses could seem like a very minor yet strange thing to him. He might tease Darcy a little about it, but all in good fun, while still being concerned about her well - being.
It could be Voldemort. Voldemort might use Harry's love as a weapon against him. He could either kill her or turn her against Harry. Another possibility is Draco Malfoy. Maybe Draco tricks Harry's love into thinking he's a better choice. Or it could be a new, unknown dark wizard who targets Harry through his love.
He might inherit the power of lightning, just like Thor. So he could be able to summon lightning bolts during battles, which would be a great addition to his existing water - based powers.