Paxton hesitated, before a big smile crept on his features. "Idiot," he said lovingly as he halted his advance. For a demon, there was no greater folly than swearing on something. A demon had to live by their word: there was no way out of it. Sure, they might be able to word their promises cleverly, creating loopholes for themselves, but...
Hm. Something occurred to Paxton.
"You did just promise," the demon said, narrowing his eyes. "But, let's be more specific, shall we? Promise you will graduate the next school year. The year of '17 to '18. Do it."