Doppelgangers turned out to melt into a remarkably noxious puddle of ectoplasm, which then evaporated into thin air and left a lipid film coating whatever they puddled onto.
Nathan learned this first when he killed “Sam” and then again when he killed “Tanya” several minutes later, an act which had become remarkably easy to repeat when it arose again as he worked through the scenario.
“Just go lethal the second you have even the slightest doubt,” Honeydew had told him blandly, tossing her head and letting her hair float as though she were posing and also a character in a stylized animated show. “You can’t kill me, and you can’t kill Tanya, but anything pretending to be one or the other of us?”
“And Honey will kill anything she sees pretending to be me,” Tanya explained, “and both of us can tell the difference between Saucer and anything that the Dungeon can conjure up.”
“That easy to tell, huh?”
“It’s… pretty fucking obvious, yeah.”
“It is,” Honeydew agreed. “Saucer radiates a mixture of magic, unmagic, and antimagic which is simply unmistakeable and which intimates a certain… well. Ancient and terrifying degree of power? And sure, anything can do magic, and a lot of things can do antimagic, and some stuff can do unmagic, but nothing can do all three at the same time. Almost nothing can even do two!”
“You can do two,” Tanya pointed out lazily. “And you keep telling me that you have an idea for how to do three.”
“Not the point,” she muttered, flushing, and then the conversation moved on.
But that conversation had left Nathan with a simple pair of rules.
First, he should kill anything and anyone that he saw, on the rationale that the scenario wasn’t rewarding them for leaving people alive. The practice would, in Tanya’s words, “be good for him” as far as rewards went, and would increase the number and quality of what was offered to him specifically; but also it would, in Honeydew’s words, “be good practice” at ruthlessly striking with lethal intent in a context where he knew that it was ethically permissible to do so.
Of course, since Honeydew and Tanya were far beyond impossible for him to kill with any realistic amount of effort—though he’d put an idle thought into it and he felt moderately confident that, with a sufficient amount of setup and a huge amount of luck, he could have a reasonable chance of killing Honeydew if Tanya weren’t around; and in fact his own evaluation of his chances were somewhat understated, as he had a somewhat higher chance of success so long as his target was thoroughly alone—he didn’t need to bother with wondering whether it was actually them when he came across “them” in the village. He would simply attack.
The second rule was that he should try, as best he could, to not be seen. To not be perceived. To, if at all possible, not raise enough of a commotion that he would wind up attracting additional enemies when, given that he would have been raising the commotion while trying to assassinate one target, he was likely to already be in a precarious position.
Stolen from its original source, this story is not meant to be on Amazon; report any sightings.
He thoroughly failed in that second one, but that was what friends were for, he figured; teaching you how to fight better, helping you learn things like magic, killing you before you wound up in a civilization worth spending a life to avoid, and casting wide-area audio-bubble spells to prevent more than a couple of people from hearing the screams, crashing sounds, cries for help, bloodcurdling battlecries, and other incidental cues for other doppelgangers to come in as support.
Well, the killing bit was atypical, Nathan acknowledged—though in this, judged by the standards of the vast majority of universes, he was only somewhat correct. A promise of a mercy killing was and is common across quite a large number of societies. Sometimes that promise took the form of end-of-life care, being a promise that the giver will not permit the receiver to deteriorate to the point of becoming an unperson in a state which inflicts only harm on others without having a genuine internal lived experience; sometimes that promise took the form of a mercy kill on the battlefield to avoid a long and protracted death, whether by disease and infection or by the influence of a demon’s corruption. An injunction and oath to kill a friend if that friend turns evil makes very little sense in a mundane world such as Earth, where the nonexistence of the soul leaves the notion of fundamental, irreversible face-heel turns risible, but in an ensouled dominion, a scar or calcification can render someone irrecoverable to the path of the common good in a way that Nathan would never have recognized.
And of course, then there were the Reborn, with the Millionborn at the most extreme end. People whose lives were a currency to themselves rather than something sublime and singular, a currency which by definition can only be expended for the benefit of others because once it’s spent there exists no Self to do the benefitting. (This is distinct from being spent for the benefit of the self; all lives are spent, in the end, and manifold are the ways in which people find personal fulfillment during the spending thereof.) And with a Reborn, and especially a Millionborn? Well, dear Reader, as we are seeing in this precise situation, one such might willingly spend their life as currency simply to avoid some awkwardness, or to save an adventuring party member after a simple job turned wrong due to an error in planning.
But we digress—Nathan did not muse or mull on any of these matters. He was, you see, rather busy.
Instead, he scaled the wall of a two-story house. His feet scrabbled for holds, but primarily he swarmed his way up to the second story by pure strength of arm, stabbing Saucer’s spikes into the wall and hoisting himself up to stab through the wall somewhat higher. In the process, he thanked his past self for the diligence of working out regularly, for all that said diligence had been consistently rewarded by an enhanced ability to be lazy about all physical activities (for being fit is very convenient in that way) and there had been no anticipation of a serial isekai-reincarnation pseudo-jumpchain existence in which he would be exerting himself in the pursuit of stealthy murder.
And speaking of murder, Nathan thought to himself distinctly, forming the words in his cognition for no particular reason, let’s see if I can do this cleanly.
He rested his feet on the narrow windowsill, bringing one hand carefully down to draw a narrow line at the very edges of the window. The sill which served as what little foothold he had was angled outwards, making it mostly unsuitable, but Saucer was bridging the gap and allowing him to anchor himself fully with one hand while also carving through the mounting of the window with the other.
Before finishing the work, he adhered a small piece of Saucer to the center of the window’s glass, and a few moments later he was having his anchoring arm nearly pulled out of its socket as he held the window up. He lowered it gently to the carpet that softened the rough wooden floors and followed it up by detaching Saucer and stretching to recover full motion in his arm.
So far, he thought to himself, so good.
And it was true.