What did satan do? For Milton, in Paradise Lost, Lucifer's reasoning was that it is "better to reign in Hell than to serve in Heaven"; his refusal to be a servant wasn't gratuitous, though, i.e. it was linked to an ultimate goal, that is, to reign. Once upon a time the most beautiful and talented angel in God's choir, as per the canon, the act of reigning was preferable for satan even though the dominion over which such reign would be exercised upon was literally a fiesta of eternal suffering besieged by lakes of fire. This whole ordeal is, fundamentally, an allegory of a moral decision in a quadrant.
First, though, we have to put this in terms that are palatable both in the physical and metaphysical realms. You know hell and heaven, right? Yes, you do. You have been to both. Succinctly, you have been to hell when suffering at all layers of your cosmogony was at its peak. Translated? Very good, here we go: Both the religious person and the non-religious person have a worldview and act upon it by ritualistic means (read the link!). They see themselves as subjects and agents of history, as the thinker Mircea Eliade elegantly put it, although the non-religious person refuses all appeals to transcendence. Since non-religious man descends from religious man, his Sisyphus tragedy is to desacralize himself, i.e. he is defined in opposition to religious man, the baseline layer of human existence. Let's see an example to ground this up: when in some culture the center of the house is, by tradition, adorned with a strong post dedicated to a religious imagery, this is nothing but the religious man recreating a worldview by a ritual in which, in order to empty himself from want, he has to put the ideal at the center, i.e. build his house on the rock instead of the sand or, put more simpler, a reminder that there are things greater than him and it is safer to base his dwelling on an aspirational model rather than his own appetites. It's symbolism, dude: the layer of human understanding where myths exist as a connection with Being, meaning, and purpose.
Juxtaposed to the non-religious man, in essence, he will also build his house with a strong center, but he will ground that decision, instead of God, on both (a) his opposition to what he sees as superstition, and (b) the fact that a house is safer if it has a strong foundational mast around which the engineering can be developed. You see? The religious man, ancient as he is, was making something commonsensical, but besides the engineering feature he was also imbuing that decision with a transcendent meaning: the center of one's world/dwelling elsewhere than on himself, as a sacrifice to a greater thing or ideal which he could not control.
So, now that we have made clear that heaven and hell can be used both for religious and non-religious realms, let's go back, shall we? Heaven is that precise moment where all the aspects of one's worldview align and make sense, plus one's health and loved ones are good, and time is occupied with meaningful things that provide purpose. It is the "time that flies", when it "all makes sense", and you feel like you are in the presence of something extremely meaningful and "everything is alright." Heaven is fleeting, as we all know, for life is a trajectory with a known end: death. Hell, instead, is profoundly stressful. It is the physical and metaphysical place where all aspects of one's worldview collide and break, plus existence is way too painful to bear. You name it: disease, misery, defeat, humiliation, confusion, addiction, loss, loneliness, etc. Hell is real and we've all been in it. Some people have lived in hell for a long time and will never get out of it.
The decision by satan wasn't a cakewalk, then. As we speculated, his decision not to serve wasn't isolated but, instead, bridged to a desire for being served. A bit reminiscent of Pascal's wager, if you like, but this quadrant illustrates the quandary in front of Lucifer when he felt he had to make a call, i.e. when his existence was unbearable via the collusion of all aspects of his Being: what he was doing, saying, feeling, and thinking were not in alignment, further clashing also with the building blocks of his worldview. He was, evidently, in a constant state of bewilderment. Look at the quadrant. In the axis of service vis-á-vis reigning, the reality is very different when put against the backdrop of the heaven/hell axis. The top right is not accessible, for in heaven there is "something greater than oneself" and, by definition, that something is in the position of primacy, of reigning. The only option in heaven, then, is to serve; you name it: to serve God, to serve others, or, in general, to serve the ideal of an existence filled with meaning and purpose. It is a place of agreement where one willingly places the satisfaction of whatever appetite the lizard brain has underneath higher, more profound things. Hell, on the other hand, offered Lucifer two options, be it servant or monarch. The worst position to be in the quadrant is to serve in hell. That is the place where one is in hell and has lost all agency. It is the place, for example, of the demented and hopeless who are too old and sick and addicted while living on the streets, without a soul in this world to help them and, most of the time, too resentful and angry to even extend the hand. Another example, hell is the place people Carl Panzram inhabited when he went on a killing rampage to quench his lunatic thirst for revenge against everything and everyone, i.e. the very fabric of existence. People like that have lost all agency and, subjects of history as they are, their hope has drained by a permanent suffering and their sense of transcendence is gone. Satan chose to serve there but, to be fair, back then the position of monarch in hell was still vacant! :)
However, reigning in hell also has its tradeoffs. By making that decision, satan attributed more moral value to what, in his worldview, was a fair state of affairs. He felt and thought that he was worthy of reigning and be served, and said and did accordingly. His cosmogony required, or so he thought, that he would be placed in a position where he was the master. The opportunity cost was to open up the box of finitude and close forever the doors to service in heaven. What the figure of satan represents in the western canon is hubris, as a consequence, but I consider this reading a bit short of what it could provide in terms of moral learning. If we go back to the homeless person in the street or to Carl Panzram, what would reigning in hell would mean? That is a situation where, indeed, hell is all around but, by virtue of some esoteric subterfuge, the subject retains his agency and sense of transcendence. Such a moral landscape, if possible at all, has two readings: (a) the state of the individual is pathologically morbid, as the obtainment of meaning seem to coexist with endless suffering, or (b) the wheels of the worldview have all been broken and, thus, the sense of moral orientation is forever gone.
This is the space inhabited by the ineffable NPC. As you can see from the reaction by the social justice snowflakes, eternally graduating from some critical theory grad school and into media or Starbucks™ barista, using the NPC meme is dehumanizing. I beg to differ. Whether one is an NPC or not depends entirely on oneself, not on others because those others do not have the capacity to alter your life beyond posting words or images online. The only way to be affected by it is, of course, you are a mental child, a snowflake who cannot turn off the damn laptop and go make his bed instead. NPC Wojak is not only perennially stuck with a blank stare which speaks tons of his empty spiritual and mental life, but, more importantly, has given up on thinking for himself. The inability of sustaining and enriching internal monologue is, by definition, the negation of all the tools at one's disposal to regain agency, build a coherent worldview, and align the elements of Being in a way of overcoming hell and achieving meaning.
Satan is, then, an NPC. A reigning NPC at that, but nothing more. By making the moral decision of declining to serve a higher goal, satan placed himself in a cage of meaninglessness where the suffering of existence is satiated solely by the worship of fallen angels. Now that the throne in hell has been occupied, the moral call at the reach of everyone is, then, to serve in heaven or to do so in hell. And, since we're all striving for heaven as an antidote to the suffering of life, the path towards that goal is sustaining constant inner monologues. The latter help discover the elements of a meaningful existence via a coherent worldview. Ideally, they then translate into coherent actions that maintain the sense of purpose throughout a path with the least presence of cognitive and moral dissonance.