A plot could involve Mugetsu Ichigo losing his memories after a battle and ending up in the Fairy Tail world. He starts to learn about Fairy Tail magic and even develops some new skills by combining his existing powers with the magic there. Meanwhile, Fairy Tail wizards are trying to figure out who he is. When a powerful enemy emerges that is related to the Soul Reaper world, Ichigo's latent memories start to return, and he and the Fairy Tail gang must work together to defeat it.
It could be Aizen from Bleach. Imagine if he somehow found a way to cross over into the Fairy Tail world. His devious and powerful nature would make him a formidable antagonist. He could manipulate the dark guilds in the Fairy Tail world to do his bidding and try to gain control over the powerful magic there, all while being a threat to Mugetsu Ichigo who he has his own history with in the Bleach universe.
Well, perhaps in this fanfiction, Ichigo in Mugetsu form is stuck in a dimension where time and space work differently. He could start losing control of his Mugetsu powers and has to learn to master them again in this new environment. Along the way, he meets a character who has knowledge about his situation and helps him on his journey, which involves facing various challenges and foes.
One great mugetsu ichigo fairy tail fanfiction could be one where Ichigo uses his mugetsu form in the Fairy Tail universe to fight a powerful dark mage. Maybe he teams up with Natsu and they combine their powers in an epic battle.
In fanfiction, mugetsu ichigo can fit in by being a mysterious new power. He could be a character that arrives suddenly and shakes up the power dynamics in the Fairy Tail world.
One possible ally could be a powerful mage from a different anime in the crossover. This mage could help Ichigo understand the strange magic or energy in the new world he is stuck in. Also, Uryu might be an ally. His Quincy abilities could complement Ichigo's powers in Mugetsu form as they face new threats together.
One idea could be that Mugetsu Ichigo finds himself in an alternate universe where he has to team up with his other - self from that universe to defeat a powerful new enemy. Maybe this enemy has the ability to nullify his Zanpakuto powers, forcing him to rely on new and creative combat strategies.
Well, 'ichigo in fairy tale mugetsu fanfiction' might be about Ichigo in a fairy - tale - like setting within a Mugetsu - related fanfiction. It could involve Ichigo having adventures in a magical world that is influenced by the Mugetsu concept. Maybe he'll encounter strange creatures or gain new powers.
The plot could involve Ichigo's unique abilities causing a stir in the Highschool DxD world. Since he has the power of Mugetsu, he could be a target for some groups who want to either use his power or get rid of him. And at the same time, he could befriend some of the characters from DxD and they could learn from each other's powers.
Another plotline could be that Ichigo is transformed into a different form due to the Mugetsu influence in the fairy tale world. He then has to learn to control this new form while also trying to break a curse that has been placed on the fairy tale world. This would involve him interacting with different fairy tale characters, some of whom might be initially distrustful of him, but as he proves himself, they become his allies.
A powerful rogue Shinigami who has turned against Soul Society and is seeking to use Mugetsu Ichigo's power for his own evil purposes. This antagonist could have some dark secrets related to Ichigo's past or his family, which would add more depth to the story.