I love these theory-forming conversations~
Ryuga makes a good point, Malladus is an anomalous addition in the lore. He's just kinda...there? We know that he was sealed away by the Lokomo in ancient times, and presumably the lore of this continent is totally estranged from that of Hyrule, but does that open up the possibility that there are indeed other realms beyond Hyrule that have things going on in them? And if so, why don't we get to know more about them?
Consider the extra-Hyrulean realms in the series: most of them take place in alternate dimensions (Termina, Koholint, Holodrum / Labrynna, Subrosia, the Sacred Realm / Dark World, the Twilight Realm, etc) and aren't a part the same physical world as Hyrule. The only realms that we know are of the same physical world as Hyrule are those realms that take place at a certain point in Hyrule's history: Skyloft exists aeons before the foundation of the Hyrulean kingdom, while the Great Sea / New Hyrule exist aeons after Hyrule has been lost under the ocean.
The only realm that we know for a fact to exist in parallel to and in the same physical world as Hyrule is New Hyrule, which is implied to have been a separate continent entirely before Link and Tetra settled there and founded a new kingdom. That's where Malladus comes into play: the lore of Spirit Tracks tells of the Lokomo tribe and the Demon King Malladus, who threatened to destroy the continent with his evil powers and was sealed away in the Tower of Spirits by the Lokomo's divine magic. Ganondorf was finally defeated for good (that we know of at this point in time) at the end of Wind Waker, having been washed away under the ocean alongside King Daphnes Nohansen Hyrule and the kingdom of Hyrule itself; since he makes no physical appearance in either Phantom Hourglass or Wind Waker, we can infer that he is, in fact, dead and gone, and therefore his demonic alter-ego, Ganon, is also dead and gone.
Yet Demise told Link and Zelda in Skyward Sword that his curse would follow their kin throughout all of eternity, and that "an incarnation" of his hatred would always appear to challenge them. We can naturally infer that this hatred is manifest as Ganondorf, chosen by the Goddess of Power as the most worthy of bearing her sacred symbol. Ganondorf's destiny seems to have two parallels drawn in this case: on the one hand, he is chosen by the Goddess of Power to receive her blessing, and thus bears the Triforce of Power, making him functionally immortal; on the other hand, the curse of Demise ensures that there will always be an evil presence within him that will seek out and attempt to destroy those we carry the spirits of Link and Zelda - does this mean the progeny of Link and Zelda specifically, or those chosen by the Goddesses of Courage and Wisdom? It's not entirely clear whether every Link is a descendant of the original Link (though it's heavily implied that some are - the Link of Twilight Princess is implied to be descended from the Link of Ocarina of Time, who manifests himself as the Hero's Shade), though we do know that every Zelda is descended from the original Zelda, the avatar of the Goddess Hylia, and all possess this aptitude for divine magic due to their divine heritage. It's not entirely clear, by extension, whether Ganondorf's destiny is connected to Link and Zelda specifically, or whether he would still target anybody else who happened to carry the Triforce of Courage and Wisdom.
What he do know is this: due to his possession of the Triforce of Power, Ganondorf cannot be killed by normal means and is, essentially, immortal. Only items blessed by divine magic and wielded by the other chosen ones, such as the Light Arrows and Master Sword, can defeat him, as even the executioner's blade wielded by the Sages was powerless to vanquish him. Even so, as he is one of the Goddesses' chosen three, he will return endlessly as long as the Triforce exists. This is where the climax of Wind Waker is interesting: Daphnes Nohansen Hyrule wishes on the Triforce that the realm of Hyrule and its past be washed away forever, in order that the descendants of its people can create a brighter future for themselves and the new world. King Hyrule and Ganondorf, as remnants of Hyrule's past, are washed away, and Hyrule itself is now nothing more than an ancient memory. Interesting to note is that the Triforce itself, as a key element of Hyrule's identity, is also washed away: it makes no appearance in either Phantom Hourglass or Spirit Tracks, and Hyrule Historia confirms that the reason why there is no Triforce emblem on the New Hyrulean royal crest is because the Triforce does not exist anymore in this timeline. Since Ganondorf's continued existence is tethered to the Triforce, as well as to Demise's curse, and there is no trace of him remaining, he cannot be resurrected anymore and will trouble the heroes of this timeline no more.
Extended detour aside, let's get back to Malladus: that we know of, Demise has no connection to the Triforce or the Goddesses, save that he wishes to attain it and achieve ultimate power (this is mentioned during Zelda's account of Skyloft's history in Skyward Sword). When he fails at this, he swears an oath of blood vengeance upon Link and Zelda (manifesting the spirit of the Goddess Hylia), telling them that his hatred will never die as long as their spirits continue to exist as well. After Ganondorf is killed, that curse seems to have vanished alongside him - unless the curse continues to live on, as Demise swore that it would, in other forms. Note how Malladus has shockingly close similarities to Demise / Ganon: the same epithet (Demon King), the same malevolent presence, the same intangible spirit and, when he possesses the body of Chancellor Cole, a true form that is very close in appearance to Ganon's appearance as a demonic boar. It must be considered whether Malladus is a fragment or incarnation of Demise's curse in the same way that Ganon is, and if so, whether Ganondorf is necessarily conceived as an avatar of Demise or is merely possessed by Demise's will. It's possible that Demise's hatred, an intangible and ephemeral spirit, actually seeks out a host to wield its enormous power - and in the wicked wills of Ganondorf and Chancellor Cole, it finds its vessel. We can even go further and theorise that every villain that has ever challenged Link and Zelda is somehow a manifestation of Demise's hatred; this would suggest that Demise's curse is not actually a physical presence or a corporeal force, but rather an analogy for evil in general. Demise is the embodiment of evil in the series, and the villains therein are embodiments of that evil by virtue of the fact that they do evil deeds and therefore, however indirectly, serve the will of Demise. Link, as the hero, is destined to fight this evil wherever it may appear and in whatever form it may adopt; and therefore, Malladus may just be an incarnation of Demise's hatred that appeared in parallel to whatever else was happening in Hyrule at the time, and Cole just happened to be the right vessel at the right time.
Apologies for the disjointed thought process, I just threw out this stuff as it came to mind. It's definitely worth considering, though - I daresay we could spend literally hours figuring this stuff out and still get no closer to discerning the truth. That's the beauty of the series. Any ideas?
) of my hatred shall ever follow your kind, dooming them to wander a blood-soaked sea of darkness for all time!"
