The Soul Reapers could be involved too. Some of them might notice that Ichigo is acting strange and try to figure out what's going on. Captains like Byakuya or Kenpachi could potentially cross paths with Ichigo during this time. And then there are the Hollows. They might sense that something is different about Ichigo but not be able to fully understand why he seems weaker than before, which could lead to some interesting confrontations.
Perhaps in the fanfiction, Ichigo hides his powers because he wants to live a normal life for a while. He could be tired of all the battles and responsibilities that come with his power. So, he tries to blend in at school and with his family, but of course, it's not easy as his true nature keeps showing up in small ways.
Another way Ichigo could get his powers back in fanfiction is through a magical or spiritual artifact. Maybe he discovers an ancient sword or a talisman that has the ability to restore his lost powers. This could be part of a grander plot where he has to go on a quest to find this item, facing various challenges and enemies along the way. During this journey, he might also learn more about the true nature of his powers and how they are connected to the overall 'Bleach' universe.
In certain fanfictions, a magical or spiritual artifact plays a crucial role in Ichigo getting his powers back. This artifact might be something that has a deep connection to his past or his family heritage. It could bestow upon him the energy or the knowledge needed to regain his powers. Maybe it was hidden away for a long time, waiting for the right moment to be discovered by Ichigo.
One possible scenario could be that Ichigo discovers his Quincy powers during a battle. Maybe he's facing an extremely powerful enemy that his existing powers can't handle, and in a moment of desperation, his Quincy powers start to emerge.
Well, the fanfic could be about Charles Xavier hiding his powers after a traumatic event. Maybe he was involved in a situation where his powers led to unintended harm. So, he decides to hide them to prevent any more disasters. He might move to a new place, change his identity, and try to live a normal life. But as time passes, he realizes that his powers are an essential part of him and that he can use them for good if he learns to control them better. He then starts a journey of self - discovery and power - reclamation.
Ichigo's powers would adapt by evolving through new challenges. In Fairy Tail, he'd face different kinds of enemies compared to Bleach. His ability to sense spiritual pressure might be tweaked to sense magic power instead. His Hollow powers, which are often seen as a dark side in Bleach, could be seen as a powerful and somewhat unruly form of magic in Fairy Tail. He would need to learn to control it better in the new environment.
It could be a powerful Quincy who sees Ichigo's newly awakened powers as a threat. This Quincy might want to eliminate Ichigo before he can fully master his powers and use them against the Quincy community.
Ichigo might gain the ability to manipulate shadows with the Darkness Zanpakuto. He could use the shadows to hide, to attack from unexpected angles, or even to create illusions. This would give him a whole new set of tactical options in battles. He could also absorb the darkness around him to strengthen his attacks or heal himself, much like how he currently absorbs spiritual energy.