Eclipse is an Eldritch God/Entity (called the Jester, or the Jester in Three Shades as a reference to the King in Yellow and the 'three shades' being the three faces/colors of their outfit) that has existed since the beginning of all things. He can view time in the same way we can view a channel on TV and check to see what's coming on later, and is physically unaffected by time (any changes to his form are made by choice), and foresaw there being a human being, who he thought of as tools for amusement and little else, that would one day best him and hold him at the point of a sword (hint: it's Y/N).
He's spent the entirety of his existence waiting for this human with baited breath, creating his own self-fulfilling prophecy: when he finally meets the object of his obsession, he's so overwhelmed he's knocked off his feet and they draw their sword (because they are confused and afraid, I mean, they've just met a really weirdly affectionate Eldritch Creature that their brain is struggling to comprehend, can you blame them??).
Y/N was trained to be a knight but decided to abandon the profession to become a scholar instead, curious about how the relationship between gods and humans came to be/what it used to look like compared to the modern day. Now they're a wandering historian, searching through the ruins of past civilizations to find bits and pieces of lost history so they can try to piece together the How and Why of the world they love.
Then they stumble upon some whack ass goofy god guy that WILL NOT stop picking them up and swinging them around while rambling like a lovesick poet. They are in WAY over their head BUT- then the god mentions that he's older than the world itself and that he's been here long enough to watch cities rise and fall, and Y/N realizes this weirdo is EXACTLY what they've been looking for.
They strike a deal- Eclipse tells them about the early days of humanity and relationship between gods and humans in general, and Y/N occasionally sometimes allows him to take them on a date. Win-win!
