My writing partner and I are nearly done with our second Harry Potter fic Ill Met by Moonlight which is a sequel to A Pound of Flesh. Not explicitly rationalist fic, but we've tried to write Riddle and Hermione smart.

One thing that's particularly fun about plotting with a partner is that we both want our character to win, (I write Hermione, he writes Riddle), so we only let the other person get away with a good trick when it delights us more as a reader than it hurts us to lose ground. Hope that pays off well for readers!