In the beginning of "The Lightning Thief", Annabeth is shown to dislike Percy when she finds out that Percy is the hero of the prophecy. She thinks he is weak, and is influenced by the rivalry between her mother, Athena, and Percy's father, Poseidon. But while they are on their quest, they have to ride a truck to get to their destination. This is the first time they actually talk. In "The Mark of Athena", Annabeth says that's when she chose to "like" him. At the very end of "The Sea of Monsters" Annabeth kisses Percy on the cheek after winning the chariot race. In "The Titan's Curse", there are suggestions of some romance between Annabeth and Percy, although this is complicated by her lingering feelings towards Luke and the fact that her mother, Athena, disapproves of her "friendship" with Percy. In "The Battle of the Labyrinth", Annabeth finally expresses her feelings for Percy by kissing him good luck before vanishing using her Yankee's cap. When Percy returns, she is highly jealous, because she knows he has been with the sad but seductive Calypso. It is implied that Percy is trying to tell Annabeth about his feelings, but Annabeth remains distant,still due to her lingering feelings towards Luke.