You and Nico had to go away from the Argo II on a side quest to fight Cupid. You put up a fight but Nico was losing energy after shadow traveling. Eventually Cupid had you bleeding from your arm and telling Nico he’d only spare you if he let go of his secret (being gay/when he had a crush on Percy). He was born in 1930 so it was scary for him to admit.

“Say it. Say it now or they die.” Cupid said.

“I.. I HAD A CRUSH ON PERCY JACKSON, HAPPY??”

Cupid disappears, pleased with himself