Okay, so the writing for this book is kind of phenomenal and terrible and contradictory since it doesn't address Katherine's thing for the threesome, but I'm gleaming some key bits to piece together that special time that was ~1864~.
( Count the parallels between Giuseppe and John Winchester )SO IN THE END, pretty weirdly written. I think Julie Plec wrote it first and then finessed it for the show later on because there's a lot of contradictions in it, like Stefan not knowing that Damon was sleeping with Katherine (in the show HE IS VERY MUCH AWARE OF THIS). But it had some interesting stuff to pick out like Anna and Pearl's backstory, Damon's time at the ~army~, THEIR MOTHER, etc.