@Cal Eh, may as well do one for Lavos since you like the character.
Chrono Trigger:
You have no idea where it came from, or its origins. You also have no idea what it is but you know one thing: It wanted to destroy the world, and it succeeded. So from the get-go it gives you the message that you're not fighting against just some monster or villain who plans to destroy the world.
You are fighting against two things: An abomination beyond the reasoning of humans and, above that, something already determined by Time and Fate itself. The main struggle of Chrono Trigger across time is about fighting against history, fate itself and how, in the end, it may be a vain struggle.
That is very much exemplified by Magus in the "What the Prophet seeks" ending:
"If history is to change, let it change! If the world is to be destroyed, so be it! If I must vanish from existence to see this done, then I shall welcome that fate!"
Without being a presence directly interfering with you, Lavos acts for most of the plot like a shadow you must confront. You don't know when or how, but you will - and with the ever heavier tone of dread the game builds up around its figure, it fortifies that sense of "inevitable" by the time you get to the Ocean Palace and the Save reads as "Lavos Beckons".
The buildup around its name,
as you reach the Ocean Palace to finally hear this start to play as you approach it more and more is amazing . Now you know that it's not a mindless monster either: It has outright created the very magic you're using so far, and it has the whole plot - Magus, Queen Zeal and others tied together to its existence. You start to realize that this isn't just about the future: Every event in this game, even prior to your time travelling, has been connected and made to happen the way it did because this thing's presence is influencing the events, making it so.
Then you finally meet it. And just like an unstoppable fate, it washes over the characters like a wave. After spending so long in preparation for fighting it, you lose everything without being able to make a single move. Not only you fail to prevent or save anything but your Silent Protagonist - the closest thing to a "player avatar" and your link to the game gets killed as well. The person you would want to save the most (Schala) sacrifices herself for you.
When you, after going through so many more changes in time and strength, finally think it defeated...
Cross comes along.
You realize that your actions ultimately changed nothing - or made it all take a turn for the worse, as the being does against you the exact same thing you did: YOU changed the Future as it should have been, so the Future - as cause and effect would have it, Fate itself strikes back at you through Lavos.
At this point the impression that the power of Lavos is like a symbol for an inevitable Fate is presented in signs all over the place. Schala saying that no physical power in the world can free her. How the scientists in El Nido refer to its power as being
"A Presence in Time, like God" and so on.
You realize the evolution of humanity, every single lifeform and timeline... It's everywhere, and later by the ending of Cross this is solidified when Lavos gets regarded as the "chosen life-form" - in the sense that everything and again, Fate, have dictated it to be so.

Only upon defeating it you get the confirmation that, despite the Planet's own efforts, the purpose of everything that exists was to lead to the creation of this one being chosen by Fate.
Then you tie that with the Game Over screens for both games and it all makes sense: The first one being "But... The Future refused to change." and the second one telling you how "Fate has no forgiveness for those who stand in its way."
And to top it all off: Despite all this, the ONE time in the whole series that Lavos actually talks to you? The thing is not at all arrogant, happy or anything you would expect from its privileged standing in existence.
It's utterly tired and finds absolute no meaning in the way existence is, which you can see clearly in its speech:
"Welcome, humans. Those who know the torment and joy of creation know also the pleasure and pain of destruction. Therefore, all that pass through here must be prepared to share the burden that I carry. In order to survive, all living things in this world, fight desperately and devour those those they defeat... Must one kill other living things in order to survive? Must one destroy another world in order to allow one's own world to continue? The wounded in turn wound and torment those weaker than they themselves are. There are only the killers and the killed... The sinners who are judged, and the victims that do the judging... What meaning is there to such a world?"
Regardless of which side of its personality said so, the Time Devourer
legitimately asks Serge's party to kill it.
Just like humans live without knowing their Fates or being able to talk to it or predict or can spend their whole lives trying to change it without knowing if its making any difference until the moment they die, you don't ever truly comprehend all there is to Lavos. Some aspects to it remain a mistery throughout the whole series, but it's honestly better that way. Ultimately, Lavos does not work like a tangible enemy most of the time - its presence and powers across time and how it influences how everyone's lifes and actions connect and play out make this being work like a representation of going against what destiny dictates... And how, by the end of the day, these actions may end up becoming exactly what makes said destiny happen, making it all meaningless. In this world, regardless of who you are, this is your life: Fighting and "devouring" one another to survive in the struggle against destiny called life.
Is it worth it? That's the question. As the Devourer, Lavos is divided in the answer: Half of it says
"No." and wants everything to disappear along with it. The other half says
"Yes." and that is what makes a chance of defeating it even possible.
...In my eyes, it sort of tells we all live sharing this same struggle each day of our lives, as Humans themselves are referred in the game as "the offspring of Lavos". It's all about not letting ourselves go down and give up to that, no matter how grim things look. Remember how they also say "Dreams" oppose Lavos? And Lavos devours Dreams? That sounds like another metaphor for the dreams we want to fulfill in life opposing Fate, but also being possibly devoured by it, making us lose hope.
