" Percy pulled Annabeth close and kissed her... long enough for it to get really awkward for Piper, though she said nothing. She thought about the old rule of Aphrodite's cabin: that to be recognized as a daughter of the love goddess, you had to break someone's heart. Piper had long ago decided to change that rule. Percy and Annabeth were a perfect example of why. You should have to make someone's heart whole. That was a much better test.
When Percy pulled away, Annabeth looked like a fish gasping for air.
'The Rivalry end here,' Percy said. 'I love you, Wise Girl. "

― Rick Riordan , The Blood of Olympus (The Heroes of Olympus, #5)