Drawing sad Percy Jackson fanart starts with capturing his emotional state—maybe after a big loss like losing a friend or failing a quest. I'd focus on his body language: slumped shoulders, a distant gaze, or clutching Riptide loosely. The setting matters too—rain works wonders for moodiness, or maybe the dim lights of Camp Half-Blood at night. Don't forget details like his necklace (if you include Annabeth's beads) or a torn sleeve from battle. Shadows under his eyes can add exhaustion, and muted blues/greys in the palette amplify the sadness.
For composition, I love close-ups of his face with raindrops or a wider shot where he's small against a vast, lonely backdrop (the beach at night? The Underworld?). If you wanna reference specific moments, 'The Battle of the Labyrinth' when he feels responsible for losses or 'The Last Olympian' during quieter, reflective scenes. Proko's YouTube tutorials on expressive poses helped me a lot!