The mystery you want solved the most

[CandleWisps]

Fucking everything thats been mentioned, with emphasis on:

Patchface (creepy lil' fuck)

What happened to/Where are Benjen and the Blackfish

Every single thing prior to present day (pretty much everything Rebellion/Summerhall)

Who Robb named as his heir in the will

What/Who is in the crypts beneath Winterfell

and finally IS RHAENYS' BALERION STILL ROAMING THE RED KEEP. I'd like to think he is.