The ending of the Shikimori manga is quite satisfying. The main characters reach a conclusion that feels right for their journey, and loose ends are neatly tied up.
I'm not sure if there is a specific fanfic with exactly that title, but it's a very common trope in fanfiction. Jealousy can add a lot of drama and tension to a story. Maybe check on popular fanfic websites and search for these characters along with the keyword 'jealous'.
One great Solangelo fanfiction where Will is jealous can be found on Archive of Our Own. It's titled 'Green - eyed Jealousy'. It really delves into Will's insecurities and how he copes with his jealousy in the relationship, all while maintaining the essence of the Solangelo dynamic.
In the fanfiction, Fem Kyuubi could be jealous of Naruto's relationships. Naruto has strong bonds with his friends like Sasuke and Sakura. Kyuubi, being trapped inside Naruto for so long, might envy those connections. She could try to interfere in Naruto's friendships by whispering negative thoughts in his mind during their interactions, hoping to drive a wedge between them.
Jealousy among siblings can be complex. However, this kind of jealousy regarding body parts is inappropriate. Instead of focusing on such physical differences, sisters should focus on building a positive relationship based on mutual respect, shared interests, and emotional support.
One possible scenario in this fanfiction could be that Sakura realizes her long - hidden feelings for Naruto when she sees Hinata getting closer to him. She might start to act out in small ways, like being a bit more snippy with Hinata during team meetings or training sessions. However, she also has to deal with her own sense of pride and the fact that she once rejected Naruto.
One manifestation could be that Leo tries to outdo Percy in various tasks. For example, if there's a competition within the story, Leo will go all out to win just to show that he's as good as or better than Percy.