"Proof" definitely ranks close to the top of creepiest Criminal Minds episodes. From beginning to end, Andy Milder plays the role of a sick fuck perfectly and the had some deranged idea when writing the episode. There the normal family drama in the episode, and then the writers introduce more family drama spanning many years that's behind comprehensible. Scary stuff.
The B plot of the episode is Reid trying to get over the lies he's endured. Reid makes snarky comments until JJ pries the information out of him. Apparently, he went to JJ crying for 10 weeks and she continued to deceive him. Obviously he doesn't feel good about this. Emily talks to Reid afterwards and tries to convince him it wasn't anyone's fault, but I don't think this is something that can be resolved in one episode. And if this topic isn't revisited, then we can blame in on the easy punching bags, the writers.
After 6 seasons of being media liaison, JJ upgrades to profiler. While I like that she has more to do now, it wouldn't been interesting to see her become a profiler from the beginning rather than this point where she's already taken classes.