I'm so happy we have the same headcanon! And I also love that idea of the Grandmaster being tired of all this superficiality and wanting something more than just another pretty face and there comes Loki and he's not only pretty but also WICKEDLY SMART (and yes also emotionally unstable but you can't have everything, besides it will only keep things more interesting and not boring so how is that any fault, really?) And wow he didn't expect that at all but he's so totally smitten with Loki.
It’s a quality headcanon, in my entirely biased opinion ;p
Everything on Sakaar is fairly surface-level, and I think that’s certainly a product of the Grandmaster’s status as one of the Elders of the Universe. Billions of years old, the guy has had to find his one obsession and invest himself wholly in it; caring about much else could bring crushing ennui. But then Loki dropped from the sky, and if he isn’t just the most interesting damn person the Grandmaster has ever met.
Emotional instability, wicked intelligence, a beguiling smirk, exquisitely chiseled bone structure, a silver tongue that charms the Grandmaster and lashes others to the bone… he’s the whole package, really. You said it exactly — the fact that Loki is a lit fuse whose reactions are as variegated as they are intense only draws the Grandmaster in further. He’s smitten. And now the Grandmaster cares about, out of everything in the entire universe, exactly two (2) things: his games, and Loki.