The Fates
From The Elysium'verse Wiki
The Fates have looked and acted the same since 1997.
You know.
...This should explain all it needs to.
Their role, for the mythologically un-inclined
The Fates know everything, and are everything. Representing Past, Present, and Future, their mythological role (same as intended here) is to carefully measure the lifespan of every mortal through the threads of life woven into the Tapestry of Fate, cutting each thread to signify where that lifespan should end. Clotho spins the thread of life; Lachesis measures its distance; Atropos cuts when time comes.
The Fates represent destiny, and all that has happened or ever will happen is specially chosen by them. The omnipotent trio have existed from the moment of creation and even the wills of the gods are dictated by their Tapestry. The Fates are neutral beings and cannot be swayed by requests or pleas to change Fate - please note the capital letter, since due to their presence the concept of Fate is always written this way. Yet upon request, they will sometimes provide cryptic prophecy depending on who's asking. The Fates do seem to have a sense of humor amongst themselves, enjoying the act of foreshadowing destinies and coincidences sometimes during their eternal actions of playing the long game.
Within Elysium canon
Within the Elysium'verse, in addition to deciding the events of all existence, their roles here have also been to act as occasional oracles of the Underworld in that way mentioned above. Previously, they were the ones to cryptically advise Hades of the destiny of an infant Melinoe, through a warning he completely ignored.
During canon, they have made several cameo appearances, mainly to give limited guidance to Tory a few times during his period of transition from mortal to Prince of the Underworld to eventual daemon.
When Loki had found himself secretly pregnant with Fjoer and ran away to hide from the palace, Tory and Thor had sought the assistance of the Fates to help locate him. The Fates are only helpful sometimes - this was not one of those times, as it turned out Loki had visited them just prior and threatened to destroy all time and space by ripping their tapestry if they were to reveal his whereabouts. Amused by his show of insane guts, the Fates elected to cover for him, assuring Tory only that he was somewhere safe, and providing no further information. (They would not have provided any information regardless).
In the way that they have decided everything that has ever happened, the Fates can also take credit for finally deciding to put an end to Thanatos, a God who had irked them through the years by meddling with the designated Fated orders to kill random mortals outside of his scope as Gentle Death. It is very possible that the bigger, biggest picture - Maci and Tory meeting in the first place, maybe even Tory's mortal birth to start with, had all been destined and leading to the birth of their daughter Neona, who was Fated in and of herself to become the new Goddess of Gentle Death. Moments like these are a perfect example of their special sense of humor, where of course Neo was born to a set of parents that Thanatos hated so severely - though the massive spiderweb pulling of strings from that far in advance is neither confirmed nor denied by them. During Maci's pregnancy, when the effects of Neo's Touch of Death in utero had spooked Tory and Maci enough to seek answers, they did (though, cryptically) confirm Neo's Fated destiny to her worried parents.
Mythological roots
The Fates fulfill their Greek mythological role, though their intended design and personality is modeled moreso after... well... you know. (Or, you should know. Yes, that. Exactly. Scroll up and reread their first bio line and then do a quick Google search and you'll know).
Still, for more information about the Fates, their Theoi page can be found here.
