It was right there in Ghost Story

If you haven't read Ghost Story, stop now.

" I murmured the most basic of ideas, the foundation of words and of **reality.**

"Be."

My universe shook. ... And in a sudden burst of silence, I stood firmly in cold, dank dimness. The cold raised gooseflesh on my skin."

\---

And ***THAT*** boys & girls, is why Uriel/The White God wanted Harry on their team. Why Hades wanted to shake Dresden's hand. Why Mab wanted Harry as the Winter Knight and she'll probably **NEVER** let him lay down the Winter Mantle.