Not everything was explained?

One of the things that stuck out to me that they didn't explain by the ending of Durarara x2 was during the "vacation" episodes, where Shinra and Celty went to [I forget where] and they saw other fantasy creatures like werewolves, vampires, etc.
During that entire vacation arc, we saw different point of views, that eventually came together in the end, except for Shinra/Celty's point of view. I remember when Shizuo called up Shinra for something, and when he hung up he said that Shinra sounded "choked up", why? What happened? And Shinra also managed to help another character by providing the exact info that he needed (I forget which character specifically), how? How did Shinra have this info? Did he happen to know it? Did someone give it to him?
I was looking forward to that entire subplot, and we never got it. Does the manga or light novels elaborate? If so, I might consider giving them a read, if only for that.


When the whole world tells you to move, you plant yourself like a tree and say "No, you move"