It wasn't the first time he'd lost it over her.
Every moment spent alone - every time they left him to his thoughts, left him unoccupied sitting on the dirty jail floor by himself, She appeared in his thoughts. First her name, softly drifting through him, and then her face. Memories would then overwhelm him; memories of Cherokee roses and holding her down while she reached out to her walker daughter; memories of her begging him to hold it together and not abandon her, not to give up on her, like everyone else already had; memories of her learning to smile again, but only for him. Only ever for him.
The memories of Carol smiling were what always made the rage come out. He'd stand up, visibly shaking, and go in search of walkers to kill. He never missed when he was firing his crossbow, never made a mistake. Heads were cut cleanly from necks, skulls cracked open. Arrows pierced cloudy, dead eyeballs. The familiar pattern kept him sane, but only as long as there were walkers to fight. It was as if every time he wasn't focused on fighting, he would feel his heart quicken and then break all over again, and he would be just like Rick. Immobilized, trapped, and going batshit crazy
When he found her knife he knew another freak out was coming on. He dropped to the ground and studied the knife, trying to hold himself together. He remembered giving the knife to her, remembered showing her the quickest and easiest ways to kill walkers with it. He remembered her teasing him about his seriousness, telling him that there was no way she would ever survive this apocalypse being as frail as she was - as much as she wanted to be as strong as him, she said she just wasn't. He had grabbed on to her shoulders and looked her straight in the eyes, making her a promise. A useless, empty fucking promise...
He stabbed at the ground, sending sharp pains up his arm. It was enough to distract him, for a moment. He imagined himself crushing those images of Carol's warm smile, stabbing the memories away. His chest ached, but he didn't stop. He hit the wall behind him, continually stabbed at the ground, lashing out as hate and rage took over. Last time he had lashed out physically, Carol had been there to bring him back to his senses. When Sophia had vanished, even though it was her daughter that had disappeared, and her heart that had broken, she had been there to remind him that it wasn't his fault. She had comforted him. Now she was gone, and he had no reason not to let himself go.
Daryl jumped to his feet when the shaking started again. A door had been rattling across from him as a walker struggled to push it against a newly fallen corpse. He kicked it in and stomped down the hall and back, not knowing how to deal with his feelings. He could howl until every walker in the damn prison went in search of him, but then... then what? He would fight to the death, and leave his fucking group, his family to die off without him? What could he do? Who knew how many walkers were behind that door? Two? Ten? Why did it even fucking matter, when the one person he needed was gone? Her body was rotting behind one of those fucking doors, mostly unrecognizable because she'd been eaten alive, had probably cursed his name as the walkers ripped her, teared her, and devoured her...
Daryl readied his knife and forced the door open, his heart pounding, wondering if his carelessness was going to cost him. Then he blinked. The room was a small, dank closet. There were no walkers, but when his eyes dropped, he saw the lifeless, drained body, and the face of the only person on the planet who could get away with teasing him, the only person who he had ever sworn to protect... and her eyes, her eyes that he had secretly thought were beautiful, blinking up at him, exhausted.
Everything stopped. Daryl's shaking, Daryl's heartbeat, everything in that moment - froze. Carol. Alive. Barely, but he could work with that. He had a chance to save her.
He reached out, cupping her chin clumsily and studying her. She was too out of it to question his actions, and he was too blind with hope and relief to care. He couldn't get on without her, he realized. He needed her.
"I've got you," he murmured, collecting her into his arms and standing. She smiled vaguely, her eyes shutting.
Despite Daryl carrying Carol to safety, he knew that again, it was she that had saved him, and she that would always be the one to save him.