A/N: This is a Christmas present for the lovely Leopard, I loved being your secret Santa and I hope you enjoy this!

Dean had never really questioned his duties before. He had always known what they were, or rather what it was. Protect Sammy, at any and all costs. That phrase had been ingrained into his very being since the day their dad had entrusted Sammy in his arms, and there was little to no thought that went into doing it; it was just a natural reflex.

Whether it be killing any monsters that approached Sam or smaller things like unconsciously standing in front of him whenever they introduced themselves, Dean protected Sam whether he knew about it or not. While he was nowhere near tall enough to hide Sam by merely standing in front of him, but his personality normally drew people's attention and more importantly, away from Sam. Most of the time he wasn't aware of his little habits; periodically glancing at Sam whenever they were on a hunt, always being a few steps ahead of Sam, checking their motel rooms, starting with Sam's bed first.

And every time Sam was injured, Dean always felt like there was something he could've done to prevent it. It was illogical, that much he knew, but it was also natural. What kind of older brother was he if he let Sam get hurt? He should've been faster, smarter, stronger, better. There was never a situation where he couldn't have done something better.

And that was what confused him when he thought about Castiel. When Dean had first met him, his feelings had been very clear. He hated him. The angel who had burned out the eyes of three innocent people, not to mention Pamela's. He had nearly caused Dean to go deaf on the assumption that he was "special". Not to mention his holier than thou demeanor. Dean hadn't deserved to be pulled out of hell and he was well aware of this. But of course, he was rescued by the biggest jackass he had ever met who continuously dangled the threat of hell in front of him and could never say something outright. Not to mention his incredibly annoying clueless attitude to any references or jokes that Dean made and his inability to think for himself. Dean had hated Castiel. With a burning passion.

As time wore on however, he found that Castiel had become more bearable. He acted more human than he had let on at first and Dean saw that he did have emotions, and a heart. He wasn't just the unthinking blunt tool that Dean had originally thought he was. Castiel had felt grief when he realized his fellow angels were being killed. He felt sympathy for Dean when revealing the difficult path that awaited them in the future, the decisions that he would have to make. Castiel had felt anger at Dean for giving up and wanting to say yes to Michael, for having to sacrifice so much for a lost cause.

And then something changed. It had started unconsciously at first. Dean hadn't noticed until Castiel himself pointed it out, and by then he was sure that this had been going on for a while without him even realizing it. Glancing at Sammy. That was a normal act, especially when they were on a hunt, but Dean knew he did it even when they weren't on hunts. He never thought twice about it, it was just something he did instinctively. Glancing at Castiel. That was not a normal act.

He had first realized it while they were hunting a werewolf in Colorado. Dean had figured it would be an easy job, werewolves only needed a silver bullet to the heart, after all. And while it was somewhat troublesome if you missed said heart, there were many other creatures that required even more tedious work to kill. So yes, werewolves were fairly simple. Sam had gotten a bad case of the flu that week and been persuaded to stay at their motel with the promise that he would bring Castiel along with him. Dean of course had agreed immediately and the pair had headed out to patrol the area where most of the murders had occurred.

"Why do you keep looking at me?" asked Castiel curiously, abruptly stopping.

"What are you talking about?" replied Dean, without looking at Castiel. He scanned the surrounding areas cautiously. Those scratch marks on the walls weren't suspicious at all. Not in the slightest.

"Approximately every minute and twenty seconds you'll turn your head and look at me," stated Castiel simply. "I wish to know why."

Dean paused for a moment, eyebrows scrunched together. He hadn't noticed before, but now that he thought of it...

"It's just a habit I have," replied Dean nonchalantly. "I'm used to checking up on Sam when we go on hunts."

The angel nodded, dropping the topic just as the werewolf decided to make an appearance.

Perhaps it was after Castiel had come back from placing the angel banishing sigil on himself. He was practically human and Dean felt something stir within him that he usually only reserved for Sammy. Protectiveness. It had first sprung up when Castiel had fallen asleep in the back seat of the Impala and it was one of the most surprising things that Dean had ever witnessed. Castiel had never really _relaxed_ per say in front of Dean, as opposed to letting his guard down ever so slightly. He always had perfect posture and spoke perfectly and everything he did was graceful and purposeful.

So to see the angel without his cover of indifference was something that Dean had burned into his mind. And while this aspect of Castiel was eye-opening, Dean was still ever concerned about the fact that angels did not sleep and that if Castiel was sleeping, something was wrong. He knew that the only reason that Castiel was in this position was because he had wanted to help, and couldn't help feel guilt well up. Castiel had given up both literally and figuratively everything to help Dean and he had nearly given up, he would've given up had Sam not been there with him.

But now that the apocalypse was over and they weren't all in immediate danger, Dean could afford to sort himself out. Castiel was an angel again complete with all of his powers restored, and Sam had gotten out of the trap. How, they weren't quite sure yet but at this point he was okay and that was all that Dean cared about. Castiel had taken quite a few months to sort out heaven however, and Dean couldn't help but feel worry gnaw away at him. Castiel didn't need any protection and Dean was well aware of it, however he did notice himself shifting in front of both Sam and Castiel whenever they went on hunts in a way that would allow him to help either should he need to. He caught himself checking on the angel as if he were going to disappear into thin air, which he did more often than not and despite his best efforts, he always felt his heart flutter irrationally because yes Castiel left often, but he always came back, so god damn it stop getting worried.

Eventually Dean realized that his tendency of checking up on Castiel were more than just a habit he picked up. He never checked up on Bobby or other hunters they teamed up with, he never felt the urge to. He also realized that what he felt for Castiel was different from what he felt with Sam. He wanted to keep Sam safe, he wanted Sam to be happy. With Castiel, he also wanted him to be happy and healthy, but with the added feeling of wanting Castiel to be happy with Dean.

And that was when Dean came to the startling conclusion that he was completely and utterly screwed.

A/N: This is a slight AU because I just finished season 5 and have yet to begin season 6, so if season 6 took a completely different direction (which is probably did), then I apologize cx