Disclaimer: I own nothing, all credit goes to the owner/creator of Percy Jackson.
Summary: Cursed so that Athena can never sense her, Annabeth is constantly attacked by monsters. At age three she was found in an alleyway by Sally Jackson and grew up as Percy's 'twin' sister. When the lighting bolt is stolen Athena slowly begins to realize that the demi-god helping Jackson is actually her own daughter.
It was all Ares' fault. That was all that the council on Olympus agreed upon. Someone had stolen Apollo's chariot for seven days and that meant a seven day eclipse for the mortal world. He may have been fun and laid back but the sun god liked his chariot and after the sixth day he was pretty mad. Ares blamed it on Athena using a framing technique so Apollo cursed her with all the power he had. Not only could she not have any more children but her youngest child who had just been born would not be able to be watched over, seen, or sensed by Athena. It started out as something that Zeus cared very little about until he realized that none of the gods, not even Apollo, could sense the presence of the child as a demi-god anymore.
He looked into the problem and revealed Ares to be the one who had stolen the chariot so that Apollo could lift the curse. Unfortunately, it was too late for them. It took three years of long debates before Zeus finally agreed that if Athena had missed three years of her daughters life then she should be allowed to get three more back. This meant that Annabeth could actually stay with the goddess in her home and no-one could blame anyone but Ares for this. When Apollo came down to the mortal world with Athena to lift the curse they found that Dr. Chase had lost Annabeth.
Naturally, the goddess was furious and demanded to know everything. All that Dr. Chase and his new wife knew was that they had left for a holiday for one week whilst leaving Annabeth in the care of a nanny who turned out to be much worse than she appeared and when they came back she was gone. The window in her bedroom was open and the nanny had drunk so much alcohol that she died in hospital a few days later. They filed a missing persons report until the issue of photographs came up and it seemed that the drunk nanny had destroyed every last one of them in her drunken state. Athena was more enraged than before and left the home after cursing Dr. Chase in many different languages and swearing that he would never see Annabeth again once she was found.
However, Athena was never going to find Annabeth since the three year old had already gotten herself into quite a mess.
After running away from home out of fear, Annabeth had used money she stole to get a train ride to New York and was attacked by many different types of monsters on the way. As you can imagine, a three year old didn't stand much of a chance and by the time of her second day after running away she was sitting in an alleyway bleeding profoundly. Without the blessing of any of the gods to help her it seemed that Annabeth was dead but this time it was sheer luck that saved her when Sally Jackson walked past and heard the crying of a little girl who was dreanched in her own blood.
Little Percy Jackson was with her at the time as they were walking home from his pre-school and he just watched in confusion as his mother calmed down the sobbing girl who was ranting about monsters that came after her because of how she smelt. Not being stupid, Sally knew at once that Annabeth was a demi-god. There was no doubt about it to her. She cleaned the child up as best she could in the alleyway and carried her back to the apartment she shared with Percy and his soon to be step-father. Ever the responsible person, Sally contacted the police to let them know about Annabeth but the girl refused to give her last name and a DNA test proved nothing at all.
After one week of staying with the Jackson's and waiting for someone to come and get her, the police gave up and said that Annabeth would be able to remain with Sally if she filled out the correct paperwork. Sally was a kind and generous person so she could hardly bring herself to send scared little Annabeth away and soon it became known to anyone who visited that Percy had a twin sister who had been very ill when she was born and had only just been allowed to return home. Gabe, the soon to be step-father, was very unsure about marrying Sally when he found out but when he found out that Annabeth's intelligence could lead to him winning every card game he played he was all for it.
So, Annabeth became Annabeth Jackson and the most intelligent person at every school she went to. The pre-school were too shocked to do anything but constantly praise Sally Jackson on raising such an intelligent child and as Annabeth grew up her grades remained at top level. As the years passed, Annabeth and Percy soon forgot about how they weren't fully related and completely believed that they were twins. When it got to the age where doctors did check-ups people were shocked to learn that Annabeth and Percy had dyslexia and ADHD. They could hardly believe that Annabeth had it whilst they had always suspected it with Percy. It was a strange time for them all.
As Annabeth and Percy turned twelve years old their futures soon became distorted by creatures that would hurt them and try to kill them. The lightning bolt had just been stolen and Zeus confronted Poseidon whilst threatening to harm Percy should the bolt not be returned. Poseidon believed that Sally had just adopted a child Percy's age to make him feel better since he did not have a father around to care for him and, due to Apollo's curse, could not sense that Annabeth was really the child of Athena. If he had, then the god might not have been so keen to have a child of his rival living under his blessing. The entire Jackson family recieved Poseidon's blessing and so Annabeth received it too. Nobody ever suspected a thing about the two children until one day in their middle school...
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