Her ledger. It was the one secret she had kept from the Red Room, and it was the one she kept from SHIELD now. It was a black leather-bound book with only twenty five thin white pages. When she worked for the Red Room, she had hid it flush against her skin, underneath the tight bodice of whatever dress she was wearing for her mission. After each kill, she would prick her finger, take out a fountain pen and etch a tally in her own blood. The red in her ledger was the product of her own pain, a small tribute to the pain she had caused.
When Clint brought her to SHIELD, she told him about the ledger. The next day, he brought her a beautifully crafted fountain pen and a small pot of black ink. Every time she saved someone, he made her put a black tally in the ledger, starting at the back of the book. He forced her to recognize that she could do good, that she could wipe the red out of her ledger if she wanted to.
Clint didn't know it, but Natasha had another set of tallies. The center two pages of her ledger were titled "When Clint Saved Me" and "When I Saved Clint." There were many more tallies on the side of debt, and more than likely she wasn't crediting herself honestly. Surely, she had saved him many more times than this.
The first tally on the page marked Clint making a different call. It was thick and dark, gone over many times. Natasha had added another layer to this mark every time he rescued her, for he wouldn't have been able to save her all those subsequent times if he had not saved her then. It was evident that she had shed a lot blood for this stroke of red in her ledger.
Natasha never told Clint about this part of his ledger. When he did find out, it was too late. Her last will and testament clearly stated that all of her possessions were to go to Clint, and that he could do with them what he saw fit. He took everything she owned and burned it, all except the ledger and the pen. In the glow of the flames, Clint flipped through the book, and his eyes fell upon the innermost pages. His stomach lurched when he found it. He took out the bloodstained fountain pen and his pocket knife. He made three precise incisions, two vertical and one diagonal to connect them, into the palm of his left hand. He took the pen and dipped it in the blood pooling in his palm around the 'N' shaped cut and drew one last tally under the heading of her saving him. Counting quickly, Clint weighed the credits and the liabilities. Clint's heart dropped out of his chest when he realized that she died the one way he knew she feared, indebted to him. He held the leather bound book over the open flames, tempted to burn it, when he saw the shadow of ink that bled through the page. He turned to the next page and found her final words, her goodbye.
Clint,
I am sorry. I'm sorry that you are reading this. I am sorry that I left you. Most of all, I'm sorry that I died with you still in my ledger. I always knew that I wouldn't break even with the world, but I wanted more than anything to ensure I wouldn't leave this earth still owing you. Countless missions done flawlessly, and I couldn't complete the only one that mattered. I'm so sorry, Clint.
Forever indebted to you,
Natasha
Clint sat in shock, and then did the one thing her never expected. He cried. He didn't sob or wail, but shed painful tears, wetting his cheeks with regret and helplessness. He blinked away his tears and looked down at the cut on his palm. He took out his knife and dug each incision deeper, ensuring that it would scar. It would serve the rest of his days as a reminder that the one person in the world whom he loved died not knowing that he would be eternally in her debt.
