"...it was that grin, that light of mischief that made his eyes bright with thinking naughty thoughts.

Not sex, though that was in there, but just a host of things he knew he shouldn't do, but so wanted to do."

Why isn't that a direct contraction?? His naughty thoughts were "not sex," even though sex "was in there" -- in his naughty thoughts? Or is "in there" somewhere else? Or -- you know what, never mind.