The Catch

I found Jack earlier. He was standing in an alleyway. I approached him.

"What the hell was up with that box?" I demanded.
"That power is my gift to you," he said.
"What's the catch?" I asked.
"What do you mean?" he asked.
"I've researched you," I said. "The wish granter, Jack Of All. You never do anything for anyone without some kind of twist."
"I honestly don't know what you're talking about," he said, mockingly.
I grabbed him by his shirt collar and pinned him to the wall.
"What's the catch!?" I demanded.
"Okay, I'll tell you," he said. "You see, in addition to giving you that power, I've given you a little something else."
"And what would that be?" I asked.
He leaned in close and whispered in my ear.
"A reason to use it," he said.

Then he vanished, without a trace.