I didn't see that comic (what was it they said she would never do?), but I did see a chat log with them discussing Boxcars' ~nightterrors~ and a hypothetical incident where PM comes to wake him up and he half strangles her and when he comes to himself manpain happens and she is the perfect understanding girlfriend. Because it's not like she has PTSD of her own or anything. And yes, it's the PM from the kids' universe.

They seem to think that Boxcars is a giant doofy teddybear they would like to cuddle with, and PM is their stand-in for that cuddling. I kind of wish more people would take the same tack as this chick whose existence I was alluding to on Tumblr and just write Mary Sues.