Percy might initially be confused. He might start to question everything that led up to the betrayal. His mind could be racing, trying to figure out if there were any signs he missed. He might also be hurt, but the confusion could overshadow the pain at first as he tries to make sense of the situation.
At first, Percy could be in shock. He can't believe that the gods, whom he has served and trusted, would betray him. But then, as the reality sinks in, he might become determined to get justice. He starts to plan his next moves carefully, using his wits and the skills he has learned over the years. He may also feel a sense of sadness and loneliness, as he realizes he is now on his own against the powerful gods.
He could be seeking revenge. After being betrayed, Percy might see Shield as a means to get back at those who wronged him. By joining Shield, he may think he can gain the power and resources needed for revenge.
He could be angry. Percy might lash out at those who betrayed him, feeling a deep sense of injustice. He would probably be determined to prove his innocence and get revenge on those who wronged him.
One possible reason could be that his friends wrongly accused him of something major. For example, if they thought he was secretly working for an enemy and didn't give him a chance to explain. Another reason might be that the gods themselves turned against him unjustly, perhaps because they feared his growing power and influence. This could make Percy feel so alone and betrayed that he decides to join Chaos as a form of revenge or to find a new place where he is accepted for who he is.
Percy might initially be in shock. He has always trusted Hestia, so when she betrays him, it would be a huge blow. He could become very angry and feel a sense of deep betrayal. He might lash out at those around him, or he could go into a state of self - doubt, wondering what he did wrong to make Hestia turn against him.
He may also try to figure out what went wrong. Percy is a smart demigod, and he would likely not just accept the betrayal without trying to understand the cause. So, he might start investigating, talking to other characters who might have some insight, like the other demigods or even some minor gods who are friendly to him.
Percy's reaction could also be one of self - doubt. He may start to question his own actions and leadership. He might think that he has done something wrong to push Annabeth away. However, his loyalty to his friends and the cause would eventually make him stand up against Kronos and try to bring Annabeth back to the right side.
At first, Percy would likely be angry. He's a fighter, and being betrayed by someone he loves would fuel his rage. He might go after Annabeth to demand an explanation. But as the reality sinks in, he could become very sad and withdrawn. He might isolate himself from his other friends as well, feeling like he can't trust anyone anymore. He would constantly be thinking about what he did wrong to make Annabeth turn on him.
He would likely be angry. Percy has a temper, and being betrayed by someone he thought was an ally would fuel his rage. He might lash out verbally or even physically, depending on the situation. For example, if they were in a battle together and Artemis suddenly turned on him, he would have to defend himself while also dealing with the emotional turmoil of the betrayal.
Percy could initially feel shock and disbelief. He might try to talk to Poseidon to find out why he was betrayed. If that doesn't work, he could become angry and lash out, perhaps even challenging Poseidon directly.