Well, it could be about Kuroko from a certain anime or manga obtaining the 'emperor eye' ability. This might lead to him having enhanced perception on the court in a sports - related context, like seeing opponents' moves before they happen and making better plays.
You could try searching on popular fanfiction websites such as Archive of Our Own (AO3) or FanFiction.net. Just type in the title or relevant keywords like 'Kuroko' and 'emperor eye' in their search bars.
A new player on an opposing team could be the cause. This new player might be overly cocky and disrespectful towards Kuroko during a game. They could constantly taunt him about his lack of presence, which finally gets on Kuroko's nerves and makes him mad.
In the fanfiction, it might be someone from his own team. Maybe there's a new member who is insecure and feels that Kuroko is getting too much attention. So, in a fit of jealousy, this person does something that causes Kuroko to get hurt, like tampering with his equipment.
Well, perhaps in the fanfiction, someone could have insulted Kuroko's basketball skills. Kuroko, usually so calm and reserved, gets mad and decides to show off his real capabilities on the court in a very intense and uncharacteristic way. He might start trash - talking his opponents, which is something he never does normally.
Well, in the 'kuroko gets sick fanfiction', perhaps his friends would take care of him. They might bring him soup and stay by his bedside to keep him company.
Perhaps an older teacher or coach who has always had an eye on Kuroko's potential could step in as a savior. They could see the signs of bullying and use their authority to punish the bullies and provide support and guidance to Kuroko, helping him to grow stronger both on and off the court.
One possible plot could be that Kuroko's quiet and unassuming nature makes him an easy target for a group of jealous basketball players. They might try to undermine his confidence before a big game by stealing his training equipment or spreading false rumors about him.
There's a fanfiction called 'Kuroko in the Shadows of Abuse'. In this story, the author uses the abuse as a way to show Kuroko's resilience. It starts with a difficult situation where Kuroko is constantly bullied and abused. But as the story progresses, Kuroko starts to find ways to stand up for himself and fight back. It's a story that shows the strength of the character in the face of such hardships. However, it's not for everyone as the topic is quite intense.