At the start, Percy would likely be in disbelief. But as things progress, he could use this new identity to his advantage. For example, he might be able to intimidate some of his enemies. However, he'd also feel guilty because he doesn't like deceiving people. Eventually, he would try to find a way to set the record straight while also using this situation to help his friends and the world he cares about.
Annabeth might be initially shocked and a bit flustered. She's a composed person, but this unexpected act from Percy would catch her off - guard. Percy, on the other hand, might be a bit proud of his 'mark' on Annabeth at first. Their friends like Grover could be really surprised and might tease them about it, while some of the more serious demigods might be a bit disapproving, thinking it's not appropriate behavior for heroes.
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 But as the reality sinks in, he could become very sad and withdrawn.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 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.
Percy would probably be angry at first. He has a strong sense of justice and being kidnapped against his will would make him fight back. He might immediately try to use his water powers to break free or at least create a distraction.
Percy would probably be cautious. He's been through a lot with the Greek gods, and he knows how powerful divine beings can be. So, he'd approach this new encounter with wariness.
Percy would feel a deep sense of guilt as well. He might think that he should have been there to protect her. So, he would be determined not only to free her but also to make sure whoever is responsible pays for what they've done. He would use his powers over water to his advantage, like creating distractions or using water to weaken the enemy's defenses while he tries to reach Annabeth.
Percy would probably be very confused at first. He's used to dealing with threats from the world of Greek mythology, not superheroes like the Avengers. But once he realizes he's been kidnapped, he'd likely be angry. He'd try to find a way to escape using his powers, like controlling water to create distractions or even using it to overpower his captors.
Percy would probably be really confused at first. I mean, one moment he's a normal demigod and the next he's a jackalope. He'd likely try to figure out what happened and how to change back right away. He might be a bit frustrated with Artemis for doing this to him without much warning.
His first reaction might be shock. Dragons aren't exactly common in his world, even with all the mythical creatures. But then his hero instincts would kick in. He could try to befriend the dragon, thinking it could be an ally in future battles against the Titans or other enemies. He might offer it some food, like a fish or something, to gain its trust.
He could be a bit shy. Since he also has feelings for Annabeth but was too nervous to make the first move. So when Annabeth asks him out, he blushes and stammers a bit, like, 'Uh, yeah, Annabeth. That sounds great.' And then he would be really happy inside, thinking about all the things they could do together on their date.