If Dark thought Dick was hard to read, he had it the other way around really. Dick thought he was difficult. He couldn't figure out what his expressions meant. Who was the true Dark? He knew he was vicious, like a leech more than a Devil. Fed off others as he'd put it. He didn't know how to respond to the partnership comment since he'd already said plans changed. So he just didn't.
If he was to answer honestly he would have to say no. While Dick enjoyed great tricks like those of Houdini or Copperfield, Dark's type of magic wasn't something he was interested in. Magic was a dangerous road. He'd seen it all too often. Raven was a prime example. Dark wasn't helping the case of positive magic in his eyes.
Oh he saw. He wondered what Dark had offered them. "I become one of you and you pack up and leave. You release them and you've got yourself a deal." Dick could already feel this was going to go sour very fast. What choice did he have? Whatever Dark had done was done, if he could at the very least save some of his team members it wouldn't be in vain. "Think about it."