I was thinking, what exactly gives you the urge to talk to your Book Bestie (BB) the second something amazing happens in your book?
Well, I'm here now to give you the answer.
As I was reading Heir of Fire (HoF) - which I'm ashamed to say, no, I haven't finished yet :'( - every time there was a huge plot twist, something new revealed about the characters, or, of course, an amazing ROWAN moment, I found myself texting my BB in all caps.
I think the main reason for this is simply that with great writing, a book can allow you to feel as if you are in the story. Non-readers wouldn't really understand. This leads me to believe that you have to unload all of this excitement/heartbreak/despair on the one person who can relate. Your BB.
It also helps tame your sequel (or 3rd book, 4th book, and so on) withdrawal. If you are DESPERATE to read the next book in the series, which "conveniently" does not come out until next September (*cough cough* Queen of Shadows *cough*), you will at least have your BB to discuss possible plots in the next book, theories you have, etc.
All in all, for the serious reader, a BB is absolutely necessary. If you do not have one, FIND one as soon as you can. It makes a world of difference to any pain you may be feeling after a favourite character's death.
Thanks, my BB, for the sweet message I found in the draft as I was halfway done this post - (Jaimie, I love this SO MUCH so far!!! EEEEP!!! - Liran)