The shadow found its master incredibly dull, and its host exceptionally cowardly. 

The latter was a good thing, of course. If the shadow was to survive, its host had to live. Yet it wasn’t convinced it could make its host leave his home to find the darkest parts of what made up the Living.

It was good at its job - to provide nightmares. Bring fear and darkness into hearts. Of course, it was only to make the lights shine brighter. Dreams, after all, were what made those of the Living unique. Made them build, grow, discover. It is what made them... good. 

What 'good' were dreams, if they never had a dark mirror? Something to run from. 

The Prince of Nightmares considered its other forms - all spirits of dreams. And the one it never met, but had heard whispers of. Its twin, the darkest part of itself. They shunned the Prince of Nightmares since their master created them to learn about the waking world. Much like the Mortals, they understood the Prince’s purpose, but never quite accepted it. 

The oh-so-perfect spirits of success, love, freedom and power. Were they not made brighter by what the Prince provided? Notions of failure, heartbreak, imprisonment, weakness? Was joy not made more beautiful by sadness, did comfort not glow more after a moment of fear?

They all underestimated it, and the power it held. 

How easy it was to break minds.

All it needed was for its host to find a sense of ambition. That, or to have it gain something he could lose.