In the end, you simply decide to follow the Example of your Companion, as your Situation wasn't going to become any less of a Mess just because you wasted valuable time on thinking about Stuff you honestly couldn't afford to change. But be that as it may, the Fact was that neither you nor your Companion could be seen as Agents of House Lannister no matter what. It was a bit bothersome that you didn't have a Way to find the Rangers of House Darway to make absolutely sure that everyone is silenced.
But seeing as most of them didn't return to neither Darway Castle itself nor Eastwend or Westwend you supposed that there was little Point in going through the Effort of hunting them down. As you're pretty sure that doing so would actually increase the Chance that one of them would inform a neighbouring House about what happened, and that absolutely wouldn't do. There's still the Possibility that the Boy might become a problem, but there was also a good Chance that he's already lying somewhere dead in the Undergrowth of one of the Forests surrounding Darway Castle, so that was that.
You spent a few more Hours thinking about what you could do to plug the more obvious Holes of your Plan till your Companion nudged you out of your Stupor as the Night had finally broken in, so you supposed that it was now or never. Darway Castle was in possession of truly formidable Defences like all true Castles of the Vale, but while the Home of the Darways was great in Size, it was clearly one of the youngest Holds that could be found in the Vale.
For Darway Castle was essentially just a fortified Cluster of Buildings that was hiding behind a total of eight great Gatehouses spread across the Mountain. It was actually why you had originally decided that burning the whole thing down was not just the flashiest, but also the easiest Way to get rid of it. As you were quite sure that House Darway didn't have the spare Resources to casually dig a Well through their Mountain, which meant that the flammable Heart of Darway Castle was most likely entirely dependent on the Water Reserves in its Cisterns if a Fire broke out.
Meaning that if you and your Companion manage to speedily infiltrate the Castle and block off or even collapse those Cisterns before the Knights of House Darway realise what's going on, there would be a decent Chance that the Fire will force them to abandon the Castle, which would split their Forces in two. They would of course still have the massive Gatehouses, but once the Clans move to surround and starve them out, those Defences won't really make a Difference when their Supplies and Messenger Birds alike have long since turned to Ash.
You actually liked this little Plan of yours quite a bit, as it gave you another relatively safe Opportunity to further increase your Value to the Lannisters, but the Death Toll that would come with your Success still bothered you. It was a bit ridiculous that you were preoccupied with this Nonsense even as you and your Companion were slowly climbing up the steep but unfortified northern Side of the Mountain. Yet you couldn't bring yourself to see the Fact that you still had a working Conscience as something bad even if it keeps on distracting you to an annoying Degree, as you've already seen what can happen to People that leave that Part of themselves behind.
When you pushed these Thoughts away to focus on the Rock in front of you a few Minutes later, you had honestly expected that your Companion would by now have a pretty difficult time as he was still clad in his Armour, despite how little Sense that made. You knew that some People were ridiculously stubborn and would go to any length just to prove that they could do the impossible, but actually climbing all the Way up the Mountain in a Suit of Plate Armour was beyond moronic. It had made you doubt his Sanity when he first started climbing, but you knew for sure that this Companion of yours wasn't nearly as dense as the Nonsense he was currently pulling made him seem, who knows, perhaps he's actually the shy kind of Guy?
Sigh, it seems like your Mind really wasn't working as it used to if the Guy that can squish grown Men into Puddles of Blood and Gore by the dozens suddenly looks shy to you, really, what a bothersome Mess this was. But at least the Plan was still working, as the northern Side of Darway Castle had at most half a dozen Guards from the little Light you could see and the sparse Amount of Dialogue you could hear another twenty or so meters above you, yes, this was absolutely doable.
And indeed it was, for while you had to climb down a bit to stop the Advance of the Knight so that the Guards wouldn't hear him, once you climbed back up and took care of the unlucky bunch of Guards the Castle was pretty much defenceless. You knew that the best way to take care of the Cisterns permanently was to take care of the Pillars, which was why you split up with your Companion as soon as he caught up with you.
As you could guess just how silent the Task of blowing out the Support Pillars would be, and seeing as the Fire would need to be laid simultaneously for maximum Chaos so that you could actually flee the burning Castle yourselves, there was no one better for the Job than your armoured Companion. For you could also guess just how difficult it would be to get out of there once everyone in the Castle tries to get to the Water before the Flames rage out of control, yes, that really wasn't a Task you were confident in surviving.
Though, you supposed that you could use it to point out how good your favourite Monster would do as an Assassin if you got the Chance to speak with your new Lords once more. You continued to think about this strange Companion of yours as the Castle swiftly fell to absolute Madness till you were finished with your Part of the Job and simply waited in the Shadow of a small Pile of Crates you were happily plundering on the currently still cleared out northern Wall. You didn't need to wait long for your Companion to finish up, as you soon found that he stood silently by your Side once more, naturally completely covered in Blood as you had expected.
But that being said, there was no reason for him to just stand by your Side in the current Situation, so you swiftly joined him to see what had caught his Interest to such an Extent. And what you found as you stared out over the darkened Lands beyond filled you with a weird Sense of Nostalgia, as the Vale was once more burning as it did the Night you had first entered it. The Madness surrounding you now both near and far filled your Face with a self-deprecating Smile as all Thoughts about the Morality of your Mission left you, while you wondered why you had even bothered to worry if this State has already become the Norm for the Lands of House Arryn.