McGregor's unruly behavior and his disrespect towards Khabib. He said things that were completely unacceptable. Khabib, being a proud fighter with strong values, couldn't let those remarks slide. So, he took on McGregor in the fight to set things straight and prove his worth in the MMA world.
There was a girl and a boy in a competition. It was a race. The boy was overconfident and made some taunting remarks towards the girl before the race. This made the girl determined to win. During the race, the boy tried to block the girl's path a few times. The girl, not one to be bullied, elbowed him gently but firmly out of the way. In the end, the girl won and the boy was left fuming. But the girl just walked away with a proud smile on her face.
Once, I saw a wife and a mistress have an argument in a park. The wife found out about the mistress and confronted her. The mistress tried to act tough at first, but the wife was full of anger and rightful indignation. The wife started shouting about how the mistress was ruining her family. In the end, the mistress, feeling ashamed, ran away.
Well, one possibility could be that Naruto somehow enters the world where Nnoitra exists. Maybe he's on a mission to understand a different kind of power system that Nnoitra has. And through their interactions, Naruto starts to learn new combat techniques and ways of thinking. He might also try to change Nnoitra's violent nature with his own ideals of friendship and perseverance.
Obviously, Naruto and Nnoitra are the main characters. Naruto, the energetic and determined ninja from the Hidden Leaf Village, and Nnoitra, the powerful and often aggressive character from another world.
Adaptation is also a key theme. Nnoitra has to adapt to new environments, whether it's a different time period, a new world with different physics, or a society with different social hierarchies. This can lead to some really interesting character development as he tries to find his place in these new situations.
Jealousy. The wife is jealous of the mistress for stealing her husband's attention and love. And the mistress might be jealous of the wife's legal position in the man's life.
In RWBY fanfiction, the Weiss vs Winter fight can be a display of their different combat styles. Weiss is more about grace and precision with her Glyphs, while Winter, being more experienced, has a more refined and perhaps harsher style. Their fight could also explore their complex relationship as sisters.
One common theme is the 'opposites attract' concept. Since Nnoitra has a rather rough and aggressive personality, the contrast with the reader's more normal or gentle nature is often explored. Another theme is the idea of redemption. Nnoitra may be seen as a character who can be redeemed through his relationship with the reader.