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.
In some fanfictions, Annabeth might start to cry. It shows her vulnerability. Despite her tough exterior, Percy's yelling could really hurt her feelings, especially if it's over something she thought they were in agreement on. This reaction can also make Percy feel guilty and prompt him to apologize.
He might get defensive. Percy has his pride, and being called stupid would likely make him try to defend his actions and decisions.
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.
Peter might be initially shocked and a bit scared. After all, Tony is like a mentor to him. But then he could become defensive, trying to explain his actions or point of view.
Percy might be a bit flustered and embarrassed. He's protective of his relationship with Annabeth, so having Magnus walk in might make him feel like their privacy has been invaded. He could quickly try to shield Annabeth or just look really shocked.
She might be heartbroken at first. She could try to jog Percy's memory by showing him things that were important to 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'd probably be shocked at first. But then her face would light up with joy. After all, she and Percy have been through so much together.
At first, it might become strained. Annabeth could be hurt and pull away from Percy. She might not want to be around him as much.
He could also become withdrawn and depressed.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.
He would probably be shocked. Percy has always trusted Annabeth, so being stabbed by her would be completely unexpected. He might initially be unable to believe what's happening.