Disclaimer: I don't own ASOIAF, even when I'm dreaming.
No one really knew what had happened at the Red Wedding, as people liked to call it. No one knew what she had gone through, having to watch as they stabbed her eldest right in the chest. Having to wonder whether her grandchild and her daughter in law were safe. Having to wonder where her other children were.
They use to call her son the Young Wolf, marveling at his skills in battle. What they didn't account for was how Walder Frey played the game, with every simple maneuver, he aligned himself with someone new. She was alone, not knowing where either of her children were. She had trusted Brienne of Tarth, and now she wondered why. She knew the Kingslayer was free, improved with his golden hand. Then where were her daughters? Brienne had broken the oath she had sworn, and she wondered what could be done.
Her dreams were still haunted by the sounds of Robb's pain in the end, of having to watch as they slayed every single northman. She wasn't sure if Edmure even remained alive, or if he had died trying to save the rest. They had made sure her eyes remained open, showing her what happened when you crossed the Freys. What had happened to them? Eddard was dead, maybe Arya too, and she hadn't heard anything about Sansa since the Purple Wedding, where Joffrey had died. The innocent child, Tommen, was now on Cersei's chopping block.
When the Freys turned on them, they killed Robb first, with a knife. They didn't stop there. They took his head off, then killing his direwolf too. She wanted to scream, but another Frey was already there, silencing her, making sure she watched. When the first northmen died, to the last, there were tears streaking down her face. All these men, every single one of them, dead. For nothing except the hope of a King in the North, because of allegiance to the Starks, and some the Tullys. She had never expected this to happen.
After the Red Wedding, she wasn't quite sure what had happened. She wasn't sure how she got away. All she knew was that she wasn't Catelyn Stark anymore, or even Catelyn Tully. She didn't understand either anymore. She didn't have the strength to believe in family, duty, and honor. She didn't even have the strength for honor. Winter wasn't coming, winter was here, as it destroyed her family. Both statements didn't fit her anymore, no, she wasn't even Catelyn anymore. There were no Lannisters, Targaryens, Freys, or Greyjoys. There was only her family, the Starks and Tullys in her mind. In her mind, because her heart was empty. Her heart didn't beat anymore, no. The Stranger had kept her alive though. Now, she was Lady Stoneheart.
I always viewed Lady Stoneheart as someone important, so thanks for reading, this is just a one-shot I think.