Ok, if Jason forgot everything when he switched camp ( like that he had a girlfriend, and his best friend, etc.), and Percy most likely forgot everything... What will happen to Annabeth and Grover and everyone? What if he meets "new" people?

SiGh, I think he will have new Friends and (dare I say it?) a new girfriend! Ahhh! Too horrid to be true! But I am afraid its how it will be!
Hopefully in the 3rd book they will all reuinte and be a big happy friendally! (family of friends)

i have a bad feeling it is gonna happend like that but reunite of percabeth is already in store.i swear on the river styx

Well if he forgets everything then he turns into somewhat of a different person right so when and if he regains his memory they are going to feel like someone elses memory. Maybe I am wrong and trust me I hope I am wrong but Percy will be not Percy anymore... Well he will be Percy just not the Percy we all know and love.
P.S. I have absolutely no idea what will become of annabeth and Percy for that matter

I think he would be like Jason, he would recieve a quest, regain pieces of his memory along the way, and maybe (hopefully) remember his feelings for Annabeth. IF not he MIGHT not remember he had a girlfriend but (most likely) he would (hopefully) remember he had at least feelings for someone
cough*** Annabeth***cough

i do NOT want percy to wake up and feel like a zombie with a girlfriend and Friends ou whatever. i hope that there is no 'mist'ified girlfriend for percy at all. i seriously wish that the demigods who he will be with in the begining will take him to be their bestie, that's all. percabeth roxx!!!!!!!

holy Zues, this question is harder than i thought.
well.. I'm just guessing that percy will have the same story as Jason, but, he will not fall ii won't say it, in <3 with a girl like jason did.

I hope Percy just arrives with two male demigods that are his mist friends. He will have no memory just riptide in his pocket, then when he sees a child of Minerva he will remember enough of Annabeth to stay away from other girls.

*Spoiler alert* Percy wakes up with one memory - Annabeths face and her name. He also remembers that she is really important to him