Ichigo might initially be in shock. He could be unable to believe that Tsukishima, who might have been a friend or at least an acquaintance, has turned on him.
He could immediately feel a sense of anger and determination. Despite the pain of the stab wound, he may start to gather his strength to fight back or at least question Tsukishima about his actions. For example, he might say something like 'Tsukishima, why did you do this?' while trying to stand his ground.
There's also a possibility that Ichigo goes into a more internalized reaction. He might start to reflect on his own actions and relationships that could have led to this situation. He may think about whether there were any signs he missed that Tsukishima was going to attack him. This could lead to a moment of self - discovery for Ichigo as he tries to make sense of the sudden betrayal.
One possible reason could be that Tsukishima is under some sort of mind control or influence from a more powerful and malevolent force. Maybe he has been deceived into believing that Ichigo is a threat to something he holds dear.
Rukia would probably be very suspicious right away. She knows Ichigo well and would notice the strange changes in his behavior. She might try to confront him and figure out what's wrong.
Well, one possible plot twist could be that Tsukishima's brainwashing of Ichigo is part of a larger plan by a hidden villain. Maybe this villain wants to use Ichigo's power for some evil purpose. Tsukishima might be forced to do this brainwashing against his will in some way.
Ichigo may grow in power and confidence. As he masters the ability to raise the dead, he could use it to his advantage in battles, which would boost his confidence and also lead to further development of his combat skills and strategic thinking.
Ichigo would also experience a period of sadness. He values his relationships, and when one is broken through betrayal, it would hurt him deeply. He might isolate himself for a while, brooding over what happened. But ultimately, he would use this experience to become stronger. He'd learn from it and be more cautious in future relationships, while still maintaining his core values of loyalty and trust.
Ichigo would probably be devastated. His trust in relationships would be severely shaken. He might become more withdrawn and focus even more on his battles and training, using it as an escape from the pain of the betrayal. He could also become more cynical about love and people in general.
Well, in these fanfictions, Ichigo's evolution is a complex process. First, his Hollowfication gives him a different perspective on his own strength. He may start to see his power as something that can not only be used for fighting but also for protecting his loved ones in a more intimate way. His evolution also includes his understanding of relationships. With the added element of lemon, he may learn to be more open - minded about love and attraction, which was perhaps suppressed before due to his focus on battles. He might become more attuned to his own desires and those of the other characters around him, leading to a more well - rounded character development.
Ichigo might develop in a more strategic way. Since it's a gamer - inspired story, he could start analyzing his opponents like a gamer does, looking for weaknesses and patterns. This would make him a more calculating fighter compared to his more impulsive self in the original Bleach.
The Soul Reapers in the Soul Society would see Ichigo as a major threat. They would likely mobilize their forces to either capture or eliminate him. Captains like Byakuya would be disappointed as he had come to respect Ichigo to some extent, and now would see him as a traitor.
Ichigo would likely be defiant. He's a fighter and would not easily submit to Aizen. He'd probably be constantly looking for a way to escape and would be sizing up Aizen's every move, trying to find a weakness.