He might get defensive. Percy has his pride, and being called stupid would likely make him try to defend his actions and decisions.
Sometimes he could just laugh it off. If he knows Annabeth doesn't really mean it in a malicious way, he might take it as a joke and not let it bother him too much. For example, he might make a witty comeback like 'Well, at least I'm not as stubborn as you!' to turn it into a light - hearted exchange.
Percy could also get quiet and brood. If he's in a particularly sensitive mood or if Annabeth's comment hits a nerve, he might withdraw and think about whether she has a point, which could lead to some self - reflection on his part.
Percy could also be hurt and go into a silent mode. He might start to question himself, wondering if Annabeth is right. He would then retreat into his thoughts, trying to figure out if his actions really did seem cowardly. This could lead to some internal conflict and self - discovery for Percy.
He could also become withdrawn and depressed.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.
She could also become cold and distant. Instead of engaging in a shouting match, she might simply walk away and give Percy the silent treatment. This can be a powerful reaction as it makes Percy realize that his yelling has pushed her away and he has to make an effort to fix things.
Sometimes, Percy gets defensive. If he feels that Annabeth is being unfair, he'll start to argue back. He'll try to explain his side of the story and defend his actions or words. In some fanfictions, this can lead to a big argument between them.
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.
She might be heartbroken at first. She could try to jog Percy's memory by showing him things that were important to them.
Well, in many such fanfictions, Percy might be extremely flustered. He could blush furiously and quickly look away, being the gentleman that he is. After all, he has deep respect for Annabeth.
He could also become angry. Percy has a bit of a temper, and he might lash out at Annabeth, demanding an explanation. He might feel betrayed, especially if he doesn't understand the real reasons behind the break - up. In his anger, he could distance himself from their mutual friends and go on solo quests to clear his head.
He could become withdrawn. Percy is a sensitive person at heart. So if Annabeth's actions are really hurtful, like if she cheats on him in a fanfic (although it's a very sad scenario), he would likely isolate himself from her and their friends. He might go off on his own to think things through and deal with his pain privately.
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.