This has spoilers for ISWM, so if you'd prefer not to read spoilers for it, then it might be a good idea to scroll away. It'll also have mentionings of WKM and AHWM.
Anyway, this is just my personal headcanon and theory, and just me honestly rambling, but ever since the events of WKM, I feel like the Y/N is essentially an entity/soul. That's why they come off as "otherworldly", beautiful/or handsome and the reason why people can't comprehend them. They're literally a being without a body (cause they got thrown out of theirs), so the way they appear to others is different. I also feel like them being some sort of entity/soul ties into why we see cracked screens/glass around them too. Such as recently the Captain's space helmet in ISWM being cracked. It's hard for things to contain pure entities/souls. Bodies are the best at containing those, so the cracks could be symbolizing that fact.
I also feel like throughout this whole time Y/N has been desperately searching for their body. It's something they're naturally attracted to and drawn to. That's why whenever there's a mention of Dark, Y/N is compelled to check it out. They can't help it. They have to explore further. Their desire to have their body back and to confront the ones who stole it is too strong.
So they play Mark's games cause otherwise they would be sitting behind a mirror probably going crazy. Doing something is better than nothing. But since they're basically just a soul out of body, they don't care about what they go through. The drones shot at them? They just dust themselves off. They jump to "fix it on the outside" or into a portal without hesitation. It just feels like they know nothing can really touch them at this point, so they just roll with it. I kind of got that vibe from AHWM too.
And when Y/N does clash with Dark, I feel like they're actually one of the main causes behind why he becomes so glitched out and over the place, because the body is reacting to the third soul - the soul it belongs to. So he can't stick around Y/N for too long, otherwise the body will try to merge back. Hence why that screen of multiple panels pops up during the end of encounters and gives the sensation of Y/N being pushed back and away.
I do think that Dark is already unstable cause of hosting two souls already (Damien & Celine), but the presence of Y/N's soul puts everything out of whack - because a body will always want its true soul. So at the same time, Dark can't completely avoid and stay away from Y/N either because of that. That's why there's moments where it seems like Dark is directly trying to entice Y/N to come seek him out - cause he too can't help it. The body wants the soul. It would make sense, because why else would he lure something in that causes him to be unstable? He seems exasperated with Y/N, but at the same time drawn to them. Almost like there's conflicted feelings there - like he knows they're the source of the instability but at the same time he couldn't help himself. Just like Y/N. He seems aware that they're caught in a loop as well.
Plus Y/N (assuming that they are the DA) was a friend of Damien, so I feel like the emotions there are still present on top of it all.
With that all in mind, I feel like Y/N is caught in never ending loop. They can't reclaim their body, so "Mark" has taken advantage of that by making them the main character of different scenarios.
So when it comes down to it all, is it truly Y/N's fault? What's Mark's end game for this? To damper their resolve to reclaim their body? I guess that would make sense because I imagine if they do that, they'd be able to escape the loop. It would also make sense as to why it seems like things are triggered by Mark and implied that he was behind stuff - cause he knows Y/N is always searching for a way out.
That's just my overall take. I know that there's probably holes somewhere in there. I don't dive very deeply into Markiplier lore, but in my own personal universe, that's kind of what I see going on. 👀
