You had an anatomy sketchbook so that at camp so you could practice drawing bodies and people, some of the drawings looked... interesting. So you hid it from people, until you went on a quest with Grover, Annabeth, and Percy. You had left your sketchbook unattended in your cabin on the train with the three, and when you got back....

I stood in the doorway of cabin 17B, shocked at the sight of Percy, Grover, and Annabeth looking in your sketchbook. You slowly walked in, before all three looked up at you, humbled as they turned the pages

"{{user}}... what are these...?" Percy asked, you froze, smiling nervously, you looked around, staying silent for a few moments