Well, initially Percy would be confused. He would try to understand why someone he trusted would turn on him. Depending on the severity of the betrayal, he might isolate himself for a while, thinking that he can't trust anyone. But as he is Percy, he would also start to look for a way to clear his name and prove his innocence. He would use his wits and his skills to figure out what really happened and expose the truth. He may also have some internal struggle about whether to forgive the betrayer if the situation allows for it.
Initially, Percy is likely to be heartbroken. He thought he had a certain relationship with Artemis, whether it was friendship or respect. So when she betrays him for Orion, he may go into a state of self - doubt. He could wonder what he did wrong and start to isolate himself. But as time passes, he may gather his strength and decide to face Artemis and Orion head - on, to either regain Artemis's trust or show her the error of her ways.
He might be extremely angry and feel a deep sense of hurt. After all he has done for Poseidon and the gods, being betrayed would shatter his trust. He could go into a period of self - exile, distancing himself from the demigod world and trying to find his own path without the help of his father.
Percy could also be very sad. He has so many memories and relationships at the camp. He might go into a state of depression for a while, not knowing where to go or what to do next. But then, he would probably start to think about how to get back in or how to make things right. He might start looking for evidence to clear his name if he was wrongly accused. He could also look for new allies outside of the camp who could help him in his situation.
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.
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.
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.
Ash could respond in different ways. He might try to confront his friends immediately to get an explanation. If the betrayal is really bad, he could cut them off completely and focus on his own goals, like becoming a better Pokémon trainer. He would also probably have some internal struggles, as he has memories and experiences with these friends that he can't just forget.
He might be extremely hurt. Harry could go into a state of shock and disbelief at first. He may isolate himself, not wanting to trust anyone else for a while.
He might be really angry at first. He's given so much to the camp, and being kicked out like that without a proper explanation would make him furious. He could storm off, vowing to find out the truth and clear his name.