Bringing back Grover is like getting to visit an old friend from high school," Riordan says.

"You spend a little time with them, and you quickly find yourself right back in the good old days! Writing about Grover is so natural and comfortable for me. He's a wonderful familiar character, but at the same time, he's grown a lot since we last saw him with Percy Jackson. He's taken on some serious responsibilities.. like saving the entire southern half of California from climate disaster."