I'll probably go with Time -- Like the title itself, Day until Night, the story revolves around with time. Like there's always a right time in everything that happened to my characters.
Like where one's past plays an important role for the story itself and how time will test them for better or for worst., or like what the main lead have said in the latest chapter : "To make everything 'right' this Time"
I see. So in reality it is less about the content of the book and more about the overall way it is written.
Haha my bad, I misinterpreted the intonation of your previous answer and scared myself a little 
thankfully it turned out that way :
You : 
Me : 
Thank you for taking interest in my introspective view of my work, it is nice to hear ! 
I am still not sure about eveything, this piece certainly means a lot to me and I interpreted it in sooooo many ways before actually giving it a definite form and sharing it with people? It is nourished from multiple personal aspects and subjects that I wished to approach all at once, and it ended being confusing as a reader (and frustrating as an author).
But one day, when the right time comes for me and if I decide taking the risk to not keep it private anymore, it should be out in a shape or another, multiple or simple, sooner or later...
we'll see ! 
is coming for you
HHmmmmm, that's a toughie, I'd have to go with eldritch. (its based off H.P. Lovecraft, I couldn't resist!)
For my short stories I'd say historical as each story is based off a different historical event.
Solid topic. 
I think for my first novel, The Faerie Dusters, the word is 'change.' For The Space Bum, the word is 'quest.' For Star Seeders, the word is 'development.'
Interesting, let's see if I can find some proper words for them:
Change The main character of this story goes through just a...massive amount of change in a fairly rapid time, both positive and negative and aside from being a romantic story, was a way to experiment with how someone reacts to various types of change in either direction. Change is something that a lot of people have to deal with and everyone reacts to differently: some people work well with change and other people have a very terrible time with even the smallest of changes. A lot of times however, in this story, the MC who does not have a good time with change, is forced to go through a lot of very, very dramatic and drastic changes in rapid succession.
Atonement Weird word, I know. Atonement means reparations or satisfaction for a wrong doing or wrong deeds, basically, it means making amends for something bad that someone has done. The story revolves around two characters: one who has caused a large amount of wrong doings and bad deeds and the other whom is the most wallflower person I've ever written. It revolves around what is considered needed to be forgiven for those deeds, beyond just an apology and what should happen if one of those deeds is bad enough to the extent where the wrongdoer themself are unable to correct it.
Revenge Alright, this story is one of the ones I had the most fun with: I am a massive fan of all sorts of horror movies, slashers/thrillers/monster movies, the works. I wanted to push the limits to what would be considered "proper" by the guidelines by writing in a style that resulted in almost every chapter being marked "Mature" due to language, gore or the themes that are depicted and talked about in the story. It was also an experiment with having a Bad Guy MC, having a character be by default Bad with no possible way of being seen as a "good guy" among those lines, A Bad Guy that is unapologetically bad and with good reason that...was quite interesting to write including having the Bad Guy character win and the "protagonist" of the story loosing. The MC had a massive slew of bad things happen to them that could not be rectified by the wrongdoers apologizing, so the MC decided "blood for blood" and took it into their own hands. It's a story about all sorts of revenge.
Acceptance. Accepting others for their differences, accepting yourself.
Friendship. Different personalities and dynamics. The ups and the downs of friendships.
In one word, the core idea behind my comic Space Pack would probably be Perspective.
How you view things can shape how you live- change your perspective and you change your life! Though this message is never overtly stated, it is underlying the story of the comic. Especially later on as the plot thickens! 
I think is..... paranoia
English is not my language number one jejeje
This is my comic. I want something romantic but with psychological horror, what you think?
https://tapas.io/series/CONNECTED2
The success of literary work depends on the way the book is written. Content is just the body of the story and varies from subject to subject.
Isaac Asimov wrote books on various subjects, yet it was the way he wrote them that made his works international bestsellers. His writing has a hook that has the reader turning page after page.
The same can be said about other very successful writers, to name just a few – Robert Howard, JRR Tolkien, Michael Crichton, James Michener, Enid Blyton, Terry Pratchett and George RR Martin. Their works create a sense of wonder that makes the reader forget reality, albeit for a short time.
Escapism, in a word, is all a good fictional story needs (regardless of the content or the characters in their assigned roles) to make a story work for me.
Disclaimer – Stated above is in entirety my opinion from personal experience and execution.
And what of you, Neverseen? What books do you read and how do those books shape your perception of story telling?