Leo fell onto Calypso's island about halfway through the House of Hades. He fell onto the island braking her dining table. When they first met, they did not feel any love in there relationship. But, through out Leo's time on the island he started to fall in love with her. Calypso, started to feel the same way by acting nicer and not closing him out. When they were building the boat to get Leo of the Island a raft comes. This particular raft only appears when Calypso has fallen in love. Before Leo goes Calypso kisses him and swears to come back to her. "I'm coming back calypso. I swear it on the river styx."
In the Blood of Olympus, Leo dies and then comes back to life and comes back to Calypso on his dragon festus. She hugs him and they "ride off into the unknown"
In the end of The Hidden Oracal, Leo comes back with Calypso and him and her are enlisted to help Apollo on his quest. Then in the next book Leo and Calypso go to Indiana with Apollo and go to the waystation house. Leo must go to camp Jupiter but once again promises to come back to go to high school with her.
This ship is relatively popular in the fandom.
- The name Leo is one of the twelve zodiac signs which has fire as it's element.
- Thalia Grace was Leo's first love interest, and she is the only one who is at least partially human. The love in question were all one-sided on Leo's part, though.
- Calypso is the first out of four love interests to genuinely have any real romantic interest in him.
- Leo is the only man who has ever reciprocated Calypso's affections and actually wanted a relationship with her.