One more scenario is if Annabeth starts to show interest in a new type of knowledge or activity that Percy doesn't understand. For example, if she gets into some really advanced ancient magic studies and Percy can't follow along. He may feel jealous of the new people she meets in that area or just feel left behind in general, fearing that he's losing his connection with Annabeth.
Another scenario could be when Annabeth is praised by others more than Percy. In the fanfic world, if there is a big celebration after a victory and Annabeth is getting all the glory for her strategic planning, Percy might feel jealous. He may think that his own contributions, like his combat skills, are being overshadowed.
A typical scenario could be when Annabeth spends a lot of time with another male character while working on a project. Percy might see them getting along really well and start to feel jealous. For instance, if they are building something together in the fanfic, like a new weapon or a structure, and Percy feels left out.
One common scenario is when another girl shows interest in Percy. For example, if a new demigod arrives at Camp Half - Blood and she's constantly around Percy, Annabeth might get jealous. She could start acting cold towards Percy or be overly critical of the new girl. Another situation could be if Percy has to go on a quest with a female partner and they seem to be getting along really well. Annabeth might worry that Percy will develop feelings for this other girl.
One scenario could be that Percy brings in a strange and cute little magical creature that he found. Annabeth, being curious, can't help but be distracted by it. He could also start singing a really off - key song that makes Annabeth stop what she's doing and either laugh or be really annoyed, but either way, she's distracted from her original task.
It could be new girls who come into the camp. They see Annabeth's position and all she has achieved, like her close friendship with Percy and her role as a leader, and they become jealous. Maybe some minor characters who have always been in the background and feel overshadowed by Annabeth.
Often in such fanfics, the theme of competition is present. Percy's jealousy could be a result of a perceived competition with another character for Annabeth's attention. This could be related to their heroic deeds. If another character is getting more praise or recognition from Annabeth, Percy might become jealous. It's a way to explore Percy's complex emotions towards Annabeth in a different light.
One possible scenario could be that Percy lies about a dangerous mission he's about to embark on. Maybe he doesn't want Annabeth to worry and so he tells her he's just going on a simple errand. Another could be that he lies about his feelings towards someone else in their group, like saying he doesn't trust a new member when in fact he does, just to avoid some potential conflict within the group that he thinks Annabeth would get involved in.
One common scenario is when Annabeth's over - intelligence leads her to overrule Percy's ideas in public. Percy, being a proud character, might get mad as he feels undermined. For instance, in a battle strategy discussion, if Annabeth dismisses Percy's plan without proper consideration just because she thinks her own is better.
In a fanfic, there could be a new powerful enemy who targets Annabeth specifically. Percy gets mad that someone would dare to go after her. He immediately jumps into action, using his water powers to create a barrier around her and then engaging the enemy in a fierce battle, showing no mercy as he is so angry about the threat to Annabeth.
Perhaps they are in a maze or a dangerous place filled with traps. Percy accidentally triggers a trap that releases a knife - like projectile and Annabeth, seeing the danger to Percy, moves quickly to shield him from it. This would show her deep loyalty and love for Percy.
Well, in many Percy - related fanfictions, if we consider Grover as Annabeth's friend, he might be jealous of Percy because Percy often gets more attention or seems to be more in the spotlight. Percy has a lot of heroic moments and is the son of Poseidon which gives him a certain status, and Grover might feel overshadowed at times.
Maybe some of Percy's mortal friends who don't really understand his relationship with Annabeth. They see how close they are and might be a bit envious of the special bond they share. For example, if Percy's friend was interested in Annabeth but knew he didn't stand a chance because of her and Percy's relationship, he could be jealous.