Everything had happened since then: wolves arriving at his grandmother’s door, the journey to Camp Jupiter, the weeks he’d spent in the Fifth Cohort trying not to be a complete failure. Through it all, he’d kept the half-burned piece of firewood wrapped in a cloth in his coat pocket. Keep it close, his grandmother had warned. As long as it is safe, you are safe.
The problem was that it burned so easily. He remembered the trip south from Vancouver. When the temperature dropped below freezing near Mount Hood, Frank had brought out the piece of tinder and held it in his hands, imagining how nice it would be to have some fire. Immediately, the charred end blazed with a searing yellow flame. It lit up the night and warmed Frank to the bone, but he could feel his life slipping away, as if he were being consumed rather than the wood. He’d thrust the flame into a snowbank. For a horrible moment it kept burning. When it finally went out, Frank got his panic under control. He wrapped the piece of wood and put it back in his coat pocket, determined not to bring it out again. But he couldn’t forget it.
It was as though someone had said, “Whatever you do, don’t think about that stick bursting into flame!”
So of course, that’s al he thought about.

The Son of Neptune, Chapter IX