The Battle of the Labyrinth (Percy Jackson and the Olympians, #4)

by Rick Riordan

“Yay!” he said. “Now we can eat peanut butter sandwiches and ride fish ponies! We can fight monsters and see Annabeth and make things go BOOM!”

“He had a crush on a blueberry bush once,” Juniper said miserably.

“Because sometimes it is better to have someone you mistrust close to you, so that you can keep an eye on him.

“I’m Janus,” both faces said in harmony. “God of Doorways. Beginnings. Endings. Choices.”

When I got across, I looked back and saw Tyson giving Grover a piggyback ride (or was it a goatyback ride?).