In Naruto amnesia fanfiction, the theme of redemption can be seen sometimes. Maybe Naruto did something in the past that he now doesn't remember, and his amnesia gives him a chance to start anew and make up for it. Another common theme is the exploration of the past. His friends might dig into Naruto's past to help him remember, which uncovers secrets and forgotten events.
I like 'A New Start: Naruto's Amnesia'. Here, Naruto wakes up with no memory of his past, not even knowing he is a ninja. It follows his journey of rediscovery, from learning basic ninja skills again to gradually uncovering his true identity. It has some great character development.
A crossover where a Fairy Tail mage ends up in the Naruto world with amnesia. The ninja initially suspect the mage is an enemy, but as they start to understand the mage's situation, they try to help. In the process, the mage discovers new types of magic by interacting with the chakra - based techniques in Naruto, and this new knowledge could potentially change the way magic works in their own Fairy Tail world once they return.
Sasuke might also be angry. Angry at the situation, angry at whoever or whatever caused Naruto's amnesia. His anger could fuel his determination to find a cure. He would push himself and Naruto harder in training, hoping that it would jog Naruto's memory, all while trying to hide his true feelings of worry and fear for Naruto's well - being.
One interesting plot could be that Naruto forgets all his ninja skills. His friends then have to reteach him everything from the basics. For example, Sasuke might take on the role of a strict teacher, which would be a big change in their relationship.
Hinata would also play a major role. Since she has deep feelings for Naruto, she would be devastated by his amnesia. She might try to use their shared memories, like the time she confessed her love to him during the Pain attack, to jog his memory. And the Akatsuki members could also be involved in some cases. If Naruto's amnesia was caused by their actions, they might be the antagonists in the fanfiction, or they could also be trying to use his amnesia for their own purposes.
Perhaps in the Fairy Tail world, there's a forbidden spell that goes wrong. A Fairy Tail mage is trying to use it to reach a new dimension, which ends up being the Naruto world. When the mage arrives in the Naruto world, they lose their memory due to the instability of the spell. The first person they meet in Naruto is, for example, Sasuke, who is initially suspicious but then decides to help the amnesiac mage.
Well, it's difficult to say precisely. Since it's a fanfic, it could be a really wild and unorthodox take on the Naruto series. Maybe the amnesia aspect is used to create a new storyline where a character forgets their abilities or relationships. The 'cup' could be a plot device like a chalice with some magical powers. However, the use of 'tits' makes it seem like it might be a rather inappropriate or poorly written fanfic.
It could be due to some sort of psychological trauma. Perhaps X 23 witnessed something extremely terrifying or disturbing in Westeros that the mind just couldn't handle, so it blocked out all memories as a defense mechanism. For example, seeing a dragon up close in a very violent situation could be too much for the mind to process.
One common theme is identity. When Bella has amnesia, she often struggles to figure out who she is, especially in relation to her relationships with others like Edward or Jacob. Another theme is rediscovery. She has to rediscover her past, her feelings, and her place in the world she once knew.