It was like being punched in the stomach.
One moment Castiel had been bickering with Crowley, and the next a wave of emotion crashed over him. His heart raced, he felt ill, without thinking he muttered a quick 'I have to go' to Crowley before zapping himself to the bunker.
When he got there, the air was so thick with Dean's pain he was sure the hunter had been hurt, mortally wounded in some way. When Cas looked at him, though, he realized it was not that type of injury.
He almost wished it was; those injuries he could heal in a heartbeat. This, though... he could do so little to heal this hurt for Dean. When puffy green eyes met his, and all Dean could manage to choke out was his name, Cas felt himself crumble from the inside. He brought Dean into his arms, his cheek pressed against the top of his blond head.
Castiel had a feeling Mary was going to leave, ever since their stay at that hotel a few weeks back. He didn't think it had anything to do with his and Dean's fornications, but something had changed in her that weekend. He found her pouring over that journal late at night more than once after that.
Dean didn't have to speak for Cas to know what had happened.
Dean was never a loud crier, though Cas had seen the human with tears in his eyes more than once. He had always wanted to take him into his arms, as he did now, but had never had the courage. Now, with the hunters cheek resting against his shoulder, quiet tears falling onto his white shirt... he felt like a fool for not having done this sooner.
"Dean... I don't want you to think this is happening because of you..." Cas started cautiously, knowing his hunter enough to be aware that his mind would take him to this ugly place. "Mary is a strong woman, but she's not perfect, Dean. She's going through a lot..."
Dean sniffed, one hand coming up to angrily swipe tears away from his face. "Cas, she's been living here this whole time, and I've just been trying to play house while she was quietly dealing with all this shit-" Dean's words were cut short when Cas pressed his lips to the hunters, silencing him with a firm kiss.
He tasted salty and smelled like Dean; leather and sweat and gunpowder and burnt oil from the impala. Cas pressed his hands to Dean's neck, and Dean parted his lips under Castiel's his eyes closing. Castiel's heart ached, and he poured all of the love into that kiss as he could.
He broke the kiss, pressing his forehead into Dean's and forcing the hunter to look into his eyes. "This wasn't your fault, Dean." He growled firmly.
Dean sniffed, and Cas could feel his love break in his arms. "Everyone always leaves me, Cas." Dean said, his voice cracking as emotions threatened to overwhelm the angel.
He pressed kisses into Dean's hair, his forehead, down to his cheeks, before looking into his eyes once more. "I will never leave you." He promised, knowing he would promise anything to make Dean smile again, do anything to make him happy once more. They had been so full of happiness these last few weeks, seeing Dean so shattered made something break inside Castiel. "I will never leave." He repeated, capturing Dean's lips in another wet salty kiss.
Dean gripped his hands, kissing him back... Castiel could only hope that the hunter believed him.