If you like music while you read, try "A Storm is Coming" by Tommee Proffit and Liv Ash. It's perfect for David's state of mind right now.
*****
~ DAVID ~
My entire body hummed with a painful tension. A string pulled too tight, quivering under the strain.
I couldn't think. Couldn't speak. Couldn't breathe.
I hovered at Stark's shoulder while he issued orders and filled people in, making decisions and keeping everyone focused while I walked through a fog of denial and grief and sheer rage.
Memories of holding Zara, watching her life fade from her eyes, I would fall into grief, choking debilitating grief. It gave way to rage when I remembered taking the life of that piece of shit Knight who'd claimed to vow her safety to both of us, and in the end was nothing but a cold-blooded murderer.