watching something with Circe shook a few things loose so tangent but maybe it will be enjoyable.
i've always had the idea that gods and other nonhuman beings can't feel what a human might describe as a "normal" amount of anything, whether it's joy, sorrow, rage, love, or grief. they're too big for it, comparatively, and what they do feel, they feel very deeply. it grows roots, becomes a permanent part of who and what they are, it settles into their bones like silt on the seabed as it were. It Doesn't Stop, even long after the initial event takes place. even if they're the only ones left, carrying it alone.
and it's very true for Malleus/Mallora, for Sebek, and the Octatrio and my sirens. for Ortho/Malenthios. in the case of the fae, they're a more elemental type of being - sometimes a manifestation of nature itself and only slightly, if that, watered down over time, but everything for them is sharp and intense. they can't feel just one particular thing, but a collection of emotions/impressions that linger for a long while afterwards.
in the headcanons i've written for Azul and the tweels, merfolk aren't born with the capacity to feel emotion - they have to learn it from somebody who already has them. it's a kind of mirroring, but it teaches them the responses and with enough exposure it becomes second nature. but it can also be lost if they don't regularly work that "internal muscle", and getting it back after a period of self-isolation or deprivation is very difficult. but when they do learn to feel, it's deeply. emotion doesn't just pass through them and fade, it echoes. it marks them, sometimes literally, but even when they're being mischievous or petty or cruel, they can't help but put everything they have into it. there is no such thing as a "small" kind of feeling, not really. they can learn restraint, and most often tend to over time, but that doesn't change how deeply they feel - just how they express it.
for my sirens Azura and Flora it's similar, but it depends on their background and development how they approach the minefield of emotional processes. they also feel deeply and often violently, and in expressing it they can often "go overboard" from a human's perspective. especially in their song, where it'll show the most.
it makes it very dangerous for their feelings to boil over, because there is a decent chance of the response being the nuclear one: Azul draining the life-force of everyone in Octavinelle simultaneously just before his overblot, Jade's very deliberate approach to getting revenge for being betrayed/lied to being to completely and utterly break that person at the fundamental level so they'll never function again, Floyd's hyper-aggressive reactions to what rubs him the wrong way for real, Malleus stripping everyone on Sage's Island of their living autonomy and forcing them into dreams and potentially doing the same to the entire planet if left unchecked, my Ortho's genuine willingness to wipe out any and all sentient life in the universe if it gave his brother a chance at a better/happier life.
this isn't all that they are, true, but it is an inseparable part. can't have one without the other, which means that if someone's unprepared for it they could be swallowed up and digested - possibly without remorse as well. but it does mean that when they care, they do it sincerely, with their entire being.
back when i first started musing Malleus, i had a brainworm of Lilia addressing any potential partner with a warning: it isn't easy to love a Draconia. They're wild, foolish, reckless, full of pride and arrogance, and they'll take everything on a whim if it strikes them. If you can't stomach that then flee while you can. and as we saw with Maleanor, that was true. she answered to no one but herself and her own whims, and Malleus is every bit as headstrong if not more when he decides to be. asking him to be reasonable is a loaded thing, because he is a fae and fae royalty at that, and his version of "reasonable" is unlikely to match what the average person would describe it as. and from his, and the merfolk, the siren, perhaps even the godling's perspectives, it is humans that are unreasonable.
tiny, transient things who might change their minds and how they feel just like the wind shifting direction. seemingly never for long. never steady. constantly spreading and applying their own rules to everything then moving the goalpost and altering the rules as it suits them. taking and taking, rarely learning, and yet so bright that they're captivating.
what strange and peculiar wonders, and there are reasons why cautionary tales exist. you will never go unloved by me is both a threat and a promise, holding a knife at the altar and being prepared to cut out their partner's heart or their own.
but it's worth it. hell or high water or mutually assured destruction, it's worth it