author's notes;

(If you haven't read the second to last chapter yet, please do so! ^^)

I think the idea of 'alternate universes' is an idea that's hard to wrap your head around. The idea that there is another world where everyone exists, but in a slightly different fashion. What if there's a universe where phones were never invented, Hitler went into the arts career, or wearing purple underpants on your head was trendy? If you are a female student now, chances are you could be a male barber in another universe. There's an endless amount of possibilities, and there's no way that we can ever assume the number because we live in one universe, one stream of time that's destined towards one fate.

Let's think about this way: let's imagine that our world, as we know it, is on one face of a cube. The rest of the faces are other worlds. They are all different faces, different sides with different perspectives, but in the end they are all part of the same cube. 

A slider is an interdimensional being that's believed to have the ability to travel between these universes, usually through portals or wormholes. So this means that although they are from one dimension, they are able to go to other dimensions similar to their own.

Yixing is introduced as a slider, but I think he's a little more than that. 

He travels to a total of four dimensions: his home universe, Jongin's universe, the 'perfect' universe, and the universe where only he and Myungsoo exist. Jongin's universe is set in a post-apocalyptic town where almost everyone is bloodthirsty (stemming from their war and what not), while the rest take place in our modern-day S.Korea.

In general, each universe exists the same set of characters. Yixing is Jongin's parallel, because of their similar caring personality towards their loved ones (so much that it hurts) and the fact that they tend to be driven by emotions (Jongin seems to be more level-headed though). Kyungsoo and Myungsoo are parallels, with the similar name and all. They're also not human, and have a connection to mirrors (Kyungsoo can't see his own reflection due to vampirism, and Myungsoo's true siren form can be seen in one; I didn't directly state this but it's true). 

Luhan and Dongwoo are also parallels. The first is an angel and the latter would be regarded as one. Their key point is that they both sacrifice their lives to save Yixing, whether it be in his world or another. In that retrospect, Sungyeol and Sunggyu would be parallel to each other as well (note similar names), by the way they both try to kill Yixing but end up killing Dongwoo/Luhan instead.

These characters should, in theory, exist in the perfect universe as well; some just aren't mentioned. But only MyungXing exist in the world where only they exist (duh). 

The worlds are similar because of the events that happen in them, but difer by its inhabitant's reactions to those events. This is why Yixing/Jongin cannot be with their true loves. Yixing cannot be with Myungsoo because Kyungsoo had died, and Jongin cannot be with Kyungsoo because Yixing cannot accept Myungsoo for who he really is. It's not particularly anyone's fault that these things happened, they were just meant to happen and it's unavoidable.

Although I say that, I do believe the worlds revolve around Yixing a bit. That's why I say he is more than a person who travels dimensions. In theory, the universe where only he and Myungsoo exist should not exist. But he imagined it, and it became real. So really, Yixing may be more powerful than we think. On the same note, if Yixing had accepted siren!Myungsoo, perhaps Kyungsoo would have survived? We may never know. 

Siren!Myungsoo's feelings towards Yixing were real, yes. He did like Yixing when they first met, which is why he bit him in the first place. It's not certain whether or not Yixing's were also real or if they were just affected by the venom. But he did, at the end, get very drastic. If any of you were confused by the ending, after they buried Kyungsoo, Yixing travelled to the 'perfect' universe. There, he murdered his own parallel to replace him and be with the 'perfect' Myungsoo (so is that murder or suicide?). Not exactly the ideal resolution, but at least he's happy. 

Well, that's the end of 'x-d'! Be sure to send in any other questions or comments, I'd really like to hear some of your thoughts! ^^ Thanks for reading!