The Hunters were at Camp Half-Blood for Christmas and the days approaching again. A total coincidence, but Lady Artemis had had to do something personally, and so here they were. If you cared to get more specific, the Lieutenant of the Hunt, Thalia, was being dragged by Annabeth to Artemis-knew-where, because she sure didn't.
She heard a door creak open, and whispers. "Annie, what's this all about?"
"You can open your eyes now," the daughter of Athena said, letting go of her hand.
Opening her eyes, Thalia saw Annabeth standing with Percy, Grover, Juniper, Jason, Piper, Nico, Reyna (who was also visiting), and several of her other friends at Camp.
"HAPPY BIRTHDAY!" they all cheered.
"You guys... why?"
"Well, we figured that even though you're not ageing anymore, you're still getting older. We thought we'd, you know, help you keep track of time," Percy said in one of his rare "dolphin" moments (when his brain is like that of a dolphin versus seaweed).
"Thanks... wait," Thalia said, seeing Grover go to turn on the music, "it's not Jesse McCartney, is it?"
"Nope," Nico said. "Green Day."*
"Perfect."
AN: Happy Birthday, Thals! Heh, just had to put that Titan's Curse throwback in there.