Well, one reason could be that in the fanfiction, the writer might want to explore a different dynamic. Maybe Annabeth gets lured by Luke's charm that has been newly developed in the fanfic. Luke could be presented as more understanding or having a different kind of allure that attracts Annabeth away from Percy.
One great 'Percy, Annabeth, and Luke' fanfiction is 'The Bonds of Prophecy'. It delves deep into their complex relationships. Percy's loyalty, Annabeth's intelligence, and Luke's inner turmoil are all explored in a really engaging way. The story also has some great action scenes that keep you on the edge of your seat.
One great 'Percy, Luke and Annabeth Fanfiction' is 'The Lost Hero's Tale'. It really delves into the complex relationships between the three characters. It shows how Percy's loyalty, Luke's conflicted nature, and Annabeth's intelligence interact in different scenarios.
Luke might become more enraged. Since Percy has thwarted his plan to do something to Annabeth, he could seek revenge. He might start plotting more devious schemes against Percy and Annabeth, or even their friends.
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.
Percy might use his water powers. He could manipulate water to create a distraction for Luke, like making a big wave or a water spout. Then, while Luke is distracted, Percy could quickly grab Annabeth and get her to safety.
One reason could be that she's scared. The idea of becoming a mother at that point in her life might be overwhelming, and she might think she can't handle it with Percy. Maybe she wants to protect Percy from the difficulties that come with the pregnancy as well.
Well, Percy is a complex character. His reaction could depend on how much he knew about the pregnancy before Annabeth left. If it was a complete surprise, he might be in denial for a while. He could also start to blame himself, thinking he had somehow failed her. And then he might eventually turn that pain into a determination to be a better person, whether or not he ever sees Annabeth again.
Annabeth would probably be very hurt at first. She has a strong bond with Percy, and his leaving for someone else would be a huge blow to her self - esteem and her heart.