“I don't know how you persist in being so stubborn-""It's a superpower. I was bitten by a radioactive mule.”

“If you don't watch it people will force you one way or the other, into doing what they think you should do, or into just being mule-stubborn and doing the opposite out of spite.”

“Oh, excellent," Ethan Stone said. "A way out. Good thing I was sure to be bitten by a radioactive spider so I can scale these walls and ceiling and shimmy my arse right out of here."Will studied the wall shaft for a long moment. "I don't think that would work.”

“During the years of struggling to make partner, he had sometimes entertained the comical notion that making partner would imbue him with new powers, like a budding superhero who had been bitten by a radioactive spider. It appeared that any superpowers he had gained did not include the ability to pick up women in bars.”

“What's she like? The princess, I mean.""Bullheaded. She's red headed, blue-eyed, and stubborn as a mule.”

“He was stubborn as a mule, clever as a monkey, and nimble as a hare.”