" That’s not all they ever show,” John said. “They show your heart’s desire…what you most want to see-or who-at the time you’re looking.”
“Then mine must be broken,” I said. It made sense. Why wouldn’t mine be broken? I was broken, too. Or at least I hadn’t felt normal in a long time.
“Yours isn’t broken,” John said. “Considering it’s a mobile device from earth, and no mobile device from earth has ever functioned in the Underworld before, I don’t quite understand…yet.” He was looking at me speculatively. “But it did exactly what ours do. You were worried about your family, so what you were shown was your heart’s desire: the one member of your family who’s in immediate danger, and needs your-“
“Wait a minute,” I interrupted. Something dawned on me. “Was that how you always knew when I was in trouble and needed help? Like that day at school, with Mr. Mueller? And at the jeweler’s that time? Because I was the one you most wanted to see when you looked down into your-“
“Oh, look,” John said, seeming infinitely relieved by the interruption. “Here comes Frank.”
Frank was sauntering over. “Found him,” he said, with casual nonchalance.
My heart gave a swoop. Only something as monumental as my cousin finally being located could distract me from the discovery that all those times my boyfriend had rescued me from mortal peril, it had been because he’d been spying on me from the Underworld via a handheld device seemingly operated by the Fates. "

― Meg Cabot , Underworld (Abandon, #2)