I'm really shocked at how little background the Irina stuff gave us. Basically all it told us was that he went out with her. (Leaving aside all the other stuff about it.) The main scene between them seemed to almost be more about her than him!

I consider Philip to have given us two true things about his past/childhood: that "they" used to have swordfights with icicles, and the story about the gangs in Tobolsk that jumped him on the way back with milk.