Riddler nearly gets indignant until he stops and thinks about the words, parses them out. "You... think it's better to go slow than risk this, being damaged. Minimise the risk we'll inadvertently hurt one another."

And that makes sense. Ed and Oswald have both been hurt a lot, sometimes by each other's hands.

"I can do that. I know Ed can do that, but I can do it as well."