Our New Hero

He pauses for a moment, glancing up at the shift in reality he had just created, then back down at the book. An assessment of the situation would have to come first, which would involve a testing of the book's limits, assuming it had any.

Old Rule:

He pauses for a moment. Clearly there would have to be some rather substantial guidelines put in place to keep him from being affected. Best to start with those.

Old Rule: Ownership of this book is determined by the person currently holding it.

New Rule: Nobody may hold this book except the person who is currently writing in it.

There, that should wrap up any concerns about ownership.

New Rule: The owner of this book cannot be killed or otherwise harmed, mentally or physically.

A bit of a blanket rule, but he could offer stipulations later if he got bored.

New Rule: The owner of this book will remember the timeline in which they originally located this book, and will be capable of seeing into all divergent timelines created by old rules written by them.

For a moment, he considers writing in an extra clause about this not being mentally strenuous, but he'd already included his own mental invulnerability. That'd be good enough. And now it was time for a test of scale, to see just how tough this thing really was.

Old Rule: On the planet this book resides on, the sky is perceived as green by humans.

He flips the notebook closed and takes a deep breath, and as his head turns, his entire world seems to shift. Where before outside was a pleasant summer's morning, there was instead a green tint across the whole world, the normal light blue replaced by a lime green as the reflection of the sky bounced off of every pane of glass. He pauses, eyes wide, before looking back down at the notebook, and then around the coffee shop. Not a single other person seemed to notice. It was as though nothing had happened at all, at least to them.

"...holy shit."

With a slightly shaking hand, he scratches out the most recent rule, glancing back over warily and relieved to see the sunlight back to its normal hue. He pauses for a moment, and nods. This sort of thing came with responsibility...and opportunity. The only question was, what to do first?