Annabeth sees possessed Leo

I’ll give you a tour. You can steer the boat, and if you're really good I'll give you a little paper captain's hat to wear."
Octavian's nostrils flared. "How dare you — "
"It's a good idea," Reyna said. "Octavian, go with him. See the ship. We'll convene a senate meeting in one hour."
"But..." Octavian stopped. Apparently he could tell from Reyna's expression that further arguing would not be good for his health. "Fine."
Leo got up. He turned to Annabeth, and his smile changed. It happened so quickly, Annabeth thought she'd imagined it; but just for a moment someone else seemed to be standing in Leo's place, smiling coldly with a cruel light in his eyes. Then Annabeth blinked, and Leo was just regular old Leo again, with his usual impish grin.

"Back soon," he promised. "This is gonna be epic."
A horrible chill settled over her. As Leo and Octavian headed for the rope ladder, she thought about calling them back — but how could she explain that? Tell everyone she was going crazy, seeing things and feeling cold?