Disclaimer: I don't own 'Supernatural'; that should be obvious

Feedback: Much appreciated

AN: This story is set shortly after Sam and Dean have gone their separate ways in the aftermath of 'Slash Fiction', and explores Dean's thoughts on why he killed Amy Pond; given that him killing Amy when she wasn't going to keep killing humans after helping her son stands as the jerkiest thing he's ever done, I felt that it was worth exploring why he decided to kill Amy after accepting Sam's advice and letting- or at least being prepared to allow- some other creatures to live based on less evidence

The Real Reason

Why did he do it?

That was something even he wasn't sure of any more.

Given how often Sam had been right when he'd convinced Dean to take time out and think when they were dealing with a spirit or monster, he should have learned his lesson by now, and he just kept on not trusting his brother to come to the correct decision?

OK, so Sam had been completely wrong with Ruby, but considering that she'd had even other demons fooled that she was working against them, it wasn't like that was something he could hold over his brother's head forever, and that didn't mean that Sam hadn't been right when he'd convinced Dean to leave Lenore alone, or when they'd been dealing with Andy despite Dean's concerns that he was the killer they were looking for, or when he'd persuaded Dean to go along with Molly McNamara's belief that she was still alive until they'd dealt with the other ghost on that particular highway...

He'd never mentioned it out loud in case he was wrong, but sometimes he wondered if Travis was the reason that 'Jack' guy had actually regressed into a Rugaru, given that Jack had seemed to be pretty shaken up by the news of what he was at first and all the signs that someone had been tied down earlier, which would have meant that Sam could have been right that Jack wouldn't turn into a monster if they just gave him advance warning about what he might become and left him alone afterwards...

He'd taken Sam's word with less evidence to go on in the past- hell, this girl had apparently saved Sam's life by attacking her own mother when he was a kid-, and he'd killed her just because she wasn't human?

He might have defended himself at the time by saying that she would have killed others eventually, but that was just crap; she'd told Sam that she was only doing it to help her son get over an illness and after that she'd return to her usual method of harvesting brains from the corpses she worked with, and she'd given him no reason to think otherwise.

God, he'd been willing to at least try and think of a way to help Madison cope with what she was before she accepted the need to kill herself, and now he just wasted Amy when she was only killing to protect her son?

She wasn't human...!

No...

That wasn't why he'd done it, and he couldn't pretend otherwise to himself for long; it was just getting repetitive and he wasn't in the mood to deny it after all the shit that had gone down.

In the end, he knew why he'd done it; he was a git.

He'd just finished recovering from the kind of damage he'd never sustained in almost seven years of hunting independently- even when he'd had his heart damaged and needed Roy le Grange to heal him, he was still able to move on his own with a lot of effort, but a broken leg had left him more significantly handicapped and helpless-, they'd spent a few hours in the custody of some of the most terrifying creatures they'd ever seen when they were the only ones on Earth who even knew they were there, there was a whole new breed of monster out there that he didn't know how to stop and most of the Hunter community probably didn't even know existed yet, the closest friend he'd ever had who wasn't biologically related to him had betrayed him to set himself up as a god and then died before he could make up for it, his brother was potentially suffering from a mental breakdown from an experience that even he could barely imagine...

And then he'd found a Kitsune- a brain-eating thing that was killing people-, and he'd seized on the chance to have something right in front of him that he knew how to kill and just decided to vent his frustration by killing it.

He hadn't killed her because she was a monster doing it because she felt like it; he'd killed her because he wanted something to kill and she'd presented him with a good 'excuse' to vent that anger without feeling too guilty about it in the aftermath.

He might not be getting into the 'serial killer' territory that Bela Talbot had once taunted him about, but this was far too close to that area for his own comfort...

Maybe Sam had had the right idea when he'd decided to leave for a while; Dean had a feeling that he needed to do some serious self-analysis before he got back to work hunting for the Leviathans, and that was without taking into account the sheer disturbing idea of him having come face-to-face with himself as a psychotic monster once again...

One thing was for sure; the next time he felt the 'need' to go against Sam's advice when it came to killing or not killing something, he was going to make sure that he was doing it because he genuinely thought that the thing he was dealing with would kill something later, and now just because he was feeling hacked off at the world and wanted something to hit.

He'd always accepted to himself that he was a little bit twisted for enjoying this life, but he couldn't let himself do something like that the next time he hit a low; if he kept that up, how long until he became Gordon Walker, killing the supernatural for the sake of killing it?

Never, Dean thought to himself, resolutely clenching his fists as he stared at the road ahead of him.

Whatever awaited him in the future, he would not become the new Gordon Walker.

He just wished that he could be as certain that Sam would be there to help him through whatever was waiting for him later on...