Lily. Since Snape and Lily were friends when they were young, and James had a crush on Lily. Snape might have had a special connection with Lily that James desired, so he could be jealous. Also, Snape was always kind of an enigma, and that mystery around him might have made James jealous as well. He might have thought Snape had some sort of power or charm that he didn't.
In some fanfictions, it could be related to Lily. If James did something that Snape perceived as a threat to his relationship with Lily, even if it was just being overly affectionate with her in front of Snape, Snape might lash out at James. Snape had deep feelings for Lily, and any sign of James getting in the way could trigger an attack.
Themes often include rivalry. Since they were rivals at school, Snape's jealousy of James in terms of academic achievements and social status is a common aspect. Also, there's the theme of self - loathing. Snape might be jealous of James' confidence and self - assurance, while he himself is full of insecurities, which is often explored in these fanfictions.
One reason could be jealousy. Snape might be jealous of James' popularity and charm. James, on the other hand, could be jealous of Snape's close friendship with Lily in their early years. Another reason is their different personalities. James was outgoing and bold, while Snape was more introverted and brooding. Lily might be attracted to different aspects of each of them, which could lead to the fight as they both compete for her attention.
Yes, there are several. You can try searching on fanfiction platforms like Fanfiction.net or Archive of Our Own. Look for tags related to 'James Potter', 'Severus Snape' and 'jealousy'. Some works might explore James' jealousy due to Snape's closeness to Lily or Snape's skills in potions and magic.
There are indeed such fanfictions. A lot of them focus on Snape's envy of James. It could be because of James' popularity, his natural talent at Quidditch, or his relationship with Lily. In these fanfictions, the authors often try to get into Snape's head and show how those feelings of jealousy manifested and affected his actions.
One reason could be that James finally realizes the extent of his bullying. In the original story, James often harassed Snape. In fanfiction, he might come to understand how much pain he caused Snape and feel genuine remorse. Another reason could be that he discovers new information about Snape that makes him see Snape in a different light. For example, he might find out about Snape's love for Lily and how his actions towards Snape affected Lily as well.
Perhaps in the fanfiction, James is seen as more accepting of Lily's friends and her social circle. Snape, on the other hand, might be associated with a darker crowd or have some beliefs that Lily doesn't agree with. For example, if Snape is too involved with the Dark Arts in the fanfiction, it could be a turn - off for Lily.
Hancock's charm could be a reason. She has a unique allure that might make Nami feel inferior. Maybe Hancock gets more attention from male characters.
Differing ideologies during the wizarding war. If James was seen as a threat to Snape's side (even if Snape was on the wrong side, from a moral perspective), Snape could justify killing him. For example, if James was too aggressive in fighting the Death Eaters and Snape thought it would lead to more bloodshed, he might take matters into his own hands to stop James.
One possible theme could be redemption. Maybe James realizes the wrongs he did to Snape and the kiss is a sign of his attempt to make amends. Another theme could be a change in their relationship dynamics, from enemies to something more complex. For example, a sudden realization of a deeper connection.