Ever since Dean had told you he too was part of Cas's vision, you had taken to pacing your room, mulling over its meaning for hours and days since then, not sharing all with Dean. It was not lost on you that your old feelings for him seem to be taking a hold on you again.
Back in a different life, a different world, Dean had been your guilty pleasure. You had loved the show, but Dean is what kept you hooked. He had been no less than perfect in your eyes, and, in your opinion, no other fictional character came close. But it was more than that. You had found comfort in him because of how you saw yourself in him. Your complicated relationship with your family, your taste in food, your sense of humour, your role of protector and defender, all of these had linked you with Dean Winchester, and despite not being real, he felt like a part of you.
This was before you had met the real Dean Winchester. The shock of finding him standing before you had erased the feelings you had felt prior. They did not stay gone for long, however. Overtime, you had grown closer to the real Dean Winchester. A certain comradery had developed between the two of you, distinct from the relationship either of you had with Sam or Cas. Your old feelings for him had resurfaced, but more real and complex than ever. But of course, you could not tell him this. Despite your good relationship, you could not imagine him caring for you in that way.
Dean mulled over the emotions running through him; it scared him to be feeling this way for someone. Caring for Sam as a little brother had been his job since childhood. It was natural and normal. His friendship with Cas was forged and cemented over the years where they had both fought and died for each other. But these particular feelings were new and sudden. At first Dean had brushed it aside. This was nothing new. He had been with a lot of women, and he had gotten over even more. But as time went on that nagging feeling became more and more entrenched in his mind. Ignoring it was not a solution but acknowledging or expressing it was out of the question. Dean was not someone who could have a normal life, a relationship, start a family.
At first he chose to distance himself as much as possible. However, being cooped up for days at a time in a bunker with no more than two other people made it impossible to ignore her without being obvious about it. And Dean often found himself in her company. Truth be told, he had stopped trying very hard to stay away. There was a calming effect her presence had on him, something he had rarely felt elsewhere and thus sought out often. It didn't hurt that she often told the same dumb jokes that made Sam roll his eyes, or that she listened to the same music and watched the same embarrassing shows in secret. But there was more than that. It felt like she could read his mind and emotions and vice versa and quite often they found themselves thinking in tandem. Either way, it was too dangerous to speak out loud. Besides, Dean did not want to make her life more difficult by making it awkward for her to be around him. To say nothing of the danger she would be in if anyone from his past, people and monsters alike, who he had harmed found out that there was another person they could use to hurt him and get revenge. No, he would treat her like a friend, like Sam or Cas. She could not be something more.
Sam and Cas had picked up on this connection between them as well. It was obvious to Sam both were hiding feelings for each other. He would not intervene, as he knew Dean would deny it, but he hoped eventually they would sort it out between them. He just hoped his brother wouldn't ruin his chance of happiness by being stubborn.
Cas had his own suspicions about what this might mean for them both. Perhaps this was the true purpose of the vision, a means through which the two would be brought together. He knew Dean would shut down this idea, so he did not bring it up. If he was right, their union would be inevitable.