Their relationship is likely to be complex. They are friends and comrades who have fought side by side many times. So, there's a strong bond of loyalty between them.
In this kind of fanfiction, they might have an adventure together. Maybe they'll face a new monster that they haven't encountered before. For example, a mythical creature from a less - known part of Greek mythology.
They might become more protective. Since they are dreaming of having a daughter, they would start to think about all the potential dangers she could face. Their relationship could grow deeper as they bond over their shared hopes and fears for their future child.
Grover could be a great addition. He could be the goofy but loyal friend who always gets caught in the middle of Percy and Annabeth's drama. For example, he might accidentally spill some secrets that cause more trouble between them. Another good character could be Clarisse. She could be the school bully who has a grudging respect for Percy and Annabeth but still tries to cause problems for them now and then.
Their relationship could become more intense. With her hearing his thoughts, they'd be more in tune with each other's feelings. It might make their bond stronger as they'd understand each other on a deeper level.
Grover could be a great addition. He's Percy's best friend, and his presence can add some comical relief to the story. For example, he could accidentally interrupt a romantic moment between Percy and Annabeth, leading to some awkward but funny situations.
Maybe in some fanfictions, Annabeth could be written as betraying Percy's trust. For example, she might side with his enemies or reveal his secrets, which would deeply wound Percy emotionally.
There might be such fanfiction out there in the vast world of fan - created content. However, this kind of plot goes against the original relationship dynamics in many fans' eyes. It's important to note that fanfiction can cover a wide range of scenarios, some of which may be controversial or not in line with the general perception of the original story.
Annabeth would likely be furious at first. She has been through so much with Percy, and for him to leave her for Calypso would seem like a betrayal. But then, she might also start to reflect on their relationship and what went wrong. She could become determined to win Percy back or to move on and prove that she doesn't need him.