Annabeth could also be angry, not at Percy but at the situation or the forces that led to his death. She might vow revenge and start on a journey to find out who or what was responsible for Percy's sacrifice and make them pay. This could lead her into a whole new set of adventures and challenges as she tries to come to terms with her loss.
There could be a fanfiction where Annabeth dies due to a mysterious illness. In this story, the other characters would have to deal with the grief and the mystery surrounding her death. They might search for a cure that could have saved her, but it was too late.
One possible reason could be her deep love for Percy. She might see his life as more valuable in the grand scheme of things, perhaps because of a prophecy or a mission that only he can complete. So, she chooses to sacrifice herself to ensure his survival.
One possible reason could be that she sacrifices herself to save someone else. Maybe she jumps in front of a fatal blow meant for Percy or one of the other important demigods. Another reason could be that she makes a miscalculation in her battle strategy. She might underestimate the strength or the trickery of the giants and end up in a situation where she can't escape.
One possible scenario could be that Percy sacrifices himself to save Annabeth from a powerful and deadly monster. Maybe a huge and ancient sea creature that only Percy can hold off long enough for Annabeth to escape, but at the cost of his own life.
Well, perhaps it could be about a great battle where Percy sacrifices himself to save his friends or the world. Annabeth then cries because she has lost her beloved Percy. Maybe she blames herself for not being able to protect him, and the rest of the story could be about how she copes with this great loss, like she might try to carry on Percy's legacy or find a way to bring him back in some magical way.
He could also become withdrawn and depressed. Percy and Annabeth have a very strong bond, and her death would leave a huge void in his life. He might isolate himself from his friends and family, lost in his grief and memories of her.
On the other hand, she could try to honor Percy's sacrifice. Annabeth might focus on the reasons why Percy died for her and strive to fulfill any tasks or goals that he might have hoped she would achieve. She would carry on his legacy in a positive way, even though she is heartbroken.
Well, Annabeth is a strong character. She may start by grieving privately, not wanting to let her vulnerability show. As she is pregnant, she would feel an even greater sense of responsibility. She could start documenting stories about Percy for the baby, so that the child can know who their father was. And she would probably try to find a new purpose in life, centered around raising the baby in a way that Percy would have wanted.
Well, it would probably shatter Annabeth. Percy is her closest friend and love. His death would leave a huge void in her life. She might become more withdrawn, consumed by grief. She could also become more determined to carry on Percy's legacy in the fight against the forces they were up against.