When the final Fantastic Beasts: The Crimes Of Grindelwald trailer landed, fans may have been frustrated by the seemingly pointless spoiler reveal that Nagini used to be a girl (cursed to be a Maledictus), who will be played by Claudia Kim, but it has inspired a wider conversation. Thus-far in the Potter world, the idea of the Maledictus has never really come up: we've seen werewolves, Animagi and transfiguration that allows people to become animals (sometimes against their will in the case of the Malfoy Weasel), but the idea of a child cursed to turn into a creature over time is new.
It's not a new concept of course, with an animorphic curse mentioned in the Bible, Franz Kafka's Metamorphosis explored the untold horror of being transformed into a giant beetle inexplicably and Disney's Pinocchio used an animal-based curse to punish the boys kidnapped by the evil Coachman. For some reason - possibly because we eat them - there's a long history of fears on that front.
Even in Harry Potter, the idea of lycanthropy is explored as a curse (with JK Rowling somewhat problematically talking about it as an allegory for AIDs). though the author has clarified that being a Maledictus is entirely different to that. For instance, Nagini clearly cannot turn back into a human by the time she has become Voldemort's Horcrux, whereas Lupin transforms only at the time of a full moon.
The strangest thing is that we've never seen an actual Maledictus before (prompting some to accuse Rowling of invention for the sake of advancing the idea of her own genius - as if it was all just a retcon to make the ties between her two worlds seem more substantial than they were). But what if we have and we just didn't know it?
Think about what defines Nagini (and what drew Voldemort to her in the first place): she is an important magical artifact (as a VERY rare "item"), but she also exists in the space between humanity and being an animal. In essence, she is the same as him, but the difference is he transformed himself to become snake-like wilfully and hers was a curse. She has the advanced intellect of a human, including strategising, but she also retained other aspects of her humanity: loyalty, preferential treatment, aloofness and affection (sure, it was misplaced but it was there) and more than anything, awareness of human nature.
Voldemort was drawn to her in an unusually close dynamic, partly because of those traits, partly because of his dependence on her to return him to his bodily form and partly because her being a snake reinforced his link to Salazar Slytherin. But it's the human-like traits that really matter here for this theory.
What if we saw another animal in the Wizarding World who was curiously human (and no, not Scabbers because there was a clear reason for that too)? What if arguably the MOST famous animal in Harry Potter's world was also a Maledictus?
Think about it: the early books establish that Hedwig is not like other owls: her relationship with Harry is a lot like Nagini's with Voldemort. Both are marked by close affection and loyalty, both animals are strangely human in their behaviour and both - crucially - are the closest allies of their masters. Almost as if Harry is a mirror image of Voldemort in lots of different ways...
The evidence for Hedwig's former humanity is all rooted in her behaviour: she is aloof (haughty even at times, particularly when it comes to other owls) and very much a free spirit (hence her disdain for being cooped up in her cage for a long time). When Harry is isolated at Privet Drive, Hedwig's reactions and feelings mirror Harry's exactly and it's not simply that she's close to him, it's because she's LIKE him. Her ultimate sacrifice is also very, very human in that she does it out of love to protect Harry but unwittingly gives away the fact that he is the real Harry.
Could it be that Hedwig was once a human, cursed to become an owl the same way Nagini is cursed to become a snake? Could her union with Harry have been purposefully ordained by the universe, just as Harry and Voldemort's wands shared the same super-rare heart? Could she genuinely have been a Maledictus designed to mirror the Dark Lord's relationship with his own creature companion?
You'd think Rowling might have said something about it, if it were the case, but we've seen theories about the Wizarding World engaged with some years after they were first suggested. So maybe there's time yet?