Rian

“Annabeth's voice caught on the word friend. Percy was a lot more than that. Even boyfriend really didn't cover it. They'd been through so much together, at this point Percy was part of her--a sometimes annoying part, sure, but definitely a part she could not live without.”
― Rick Riordan, The House of Hades

“You’re the world to me,” I whisper onto
her lips. “I hope you never forget that.”
“I’ll never forget,” she whispers back.. “But if I ever do, for
whatever reason, I hope you’ll always find a way to remind me.”
...“Always.”
― J.A. Redmerski, The Edge of Always

“I’ve been searching a long time for something I think I lost.
I felt like I found something when I saw you back there.”
― Marie Lu, Champion

“As his raft skimmed over the water, taking him back to the mortal world, he understood a line from the Prophecy better-an oath to keep with a final breath.
He understood how dangerous oaths could be. But Leo didn't care.
"I'm coming back for you, Calypso," he said to the night wind. "I swear it on the River Styx.”
― Rick Riordan