Another factor could be her relationship with Percy. If Percy starts spending more time with another friend or seems to be getting along better with someone else, Annabeth might question her place in his life and feel insecure about their relationship.
A possible trigger for Annabeth's insecurity could be a new arrival at Camp Half - Blood. If a new demigod shows up with amazing architectural skills, Annabeth, who is known for her own skills in this area, might start to feel inadequate.
Perhaps a prophecy that mentions a great hero with skills similar to hers but seemingly more powerful could also make her feel insecure. She might worry that she's not going to be able to live up to the expectations set by the prophecy and that she'll let everyone down.
The fanfiction could also explore how Annabeth overcomes this insecurity. It might be through a series of challenges where she realizes that everyone has their own strengths and weaknesses, and that her unique combination of skills is what makes her so valuable. She could learn to embrace her insecurities as a part of her growth journey.
Annabeth could be under some kind of magical influence. In the Percy Jackson universe, there are many magical elements. She could be cursed or charmed without her knowledge. This would be a very interesting take in a fanfiction as it would add an element of mystery and also give her a chance for redemption once the truth is discovered. Also, it could be that she has some internal insecurities that she hasn't dealt with and they manifest in this way, making her act out of character.
Well, it could be about Annabeth learning to deal with this new aspect of her life while still being in the middle of her adventures. Maybe she has to quickly figure out how to manage it in a world full of monsters and quests.
One possible plot could be Annabeth trying to hide it at first. She might be worried about how the other campers, especially the boys, would react. So she tries to carry on with her normal activities like training and strategizing but is constantly distracted by the discomfort.
In this kind of fanfiction, perhaps Annabeth might start acting out of character. She could say things she normally wouldn't. For example, she might be more open about her feelings towards her friends or reveal some secrets she's been keeping.
Well, perhaps Rachel has some unique talents or abilities that catch Percy's attention. In the fanfiction, this might make Annabeth feel insecure about her own relationship with Percy. For example, if Rachel can communicate with the gods in a way that Annabeth can't, and Percy is impressed by it, Annabeth could get jealous.
One possible plot could be that Annabeth and Percy Jackson are finally in a stable part of their lives. They are married and settled. Then Annabeth discovers she is pregnant. The story could follow their journey of preparing for the baby, with Percy being overly protective and Annabeth trying to balance her normal activities with the new changes in her body. They might face challenges like dealing with the reactions of their demigod friends, some being excited and others worried about how a baby would fit into their dangerous world.
Well, one possible plot development could be the challenges she faces in her relationship while pregnant. Maybe there are misunderstandings with her partner as they both adjust to the new situation.
Perhaps Percy forgets an important promise he made to Annabeth. In their relationship, promises are significant. If he fails to keep one, like a promise to help her with a project or be at a certain place at a certain time, Annabeth would surely be mad. It could also be that Percy accidentally breaks one of Annabeth's creations or possessions, which she holds dear.
Percy would probably be an important character. He's Annabeth's close friend and love interest. His reaction to Annabeth getting her period could be interesting, like he tries to be supportive but is a bit clumsy at first.