I was thinking about the Aedra and the Daedra the other day, and how there is no real middle ground or balance between the two. There's just Aedric/Anuic and Daedric/Padomaic. No mediator or force of balance. Now perhaps balance would be the force of constant struggle between Anuic and Padomaic, but I was wondering this: could an individual potentially ascend and become both Aedra and a Daedric Prince at the same time? I know an individual can be both Anuic and Padomaic in action, but could they literally become both Aedra and Daedra? They could be like the balance/bridge between the two. Kind of how, in the Last Airbender series, the Avatar is the balance between physical and spiritual. The consequences of having a being who is both Aedra and Daedra could be kind of interesting, lore-wise.

I think about it, and it seems as if Tiber Septim was/is essentially Aedra, but was Daedric in action when he ascended to the Nine. He became part of the Nine, who are Aedra, but his actions of becoming the new part of the Nine was Daedric, in that he changed the existing pantheon. Additionally, Jyggalag was/is a Daedric Prince, yet his very sphere, order, indicates that he isn't big on change because change often brings chaos, which is the opposite of order. Additionally, Jyggalag, as Sheogorath, wanted to remain as Sheogorath forever if possible (stasis), but also wanted to be set free, back to his original sphere (change).

So the above being said, it seems Aedra and Daedra both have both Anu and Padomay in them. However, the original question remains: can a being be both an Aedra and a Daedric Prince at the same time?

PS - Sorry if I misunderstood any of the concepts above. I'm not really a TES lore buff.

Anuic/Padomaic isn't a dichotomy, it's a sliding scale. Anu and Padomay are the only absolutes, and as the Aurbis (the Grey Maybe) was born from their interplay, no spirit or mortal can ever be entirely Anuic ("white") or Padomaic ("black").

How to apply the labels "Aedra" and "Daedra" is open to interpretation and varies a bit with context, despite how purportedly "exact" their definitions are. In practice, the Aedra are apparently understood to be the original spirits who took part in creation, while the Daedra are those who did not take part.

You will run into people who will get their panties in a wad at the mere suggestion that Talos could be an Aedra. I imagine someone is preparing a tirade on that right now, if this is anything like every other lore discussion I've ever seen where the issue has been mentioned. He may not have been an original Aedra, but theoretically, there's no absolute bar to the notion that he could have gone back and fortified Convention in the same way as the Aedra after his apotheosis, and essentially become on par with them. So you can just come to whatever conclusion you favor on that.

Though there are other grey areas, like Meridia, the nearest thing to an Aedra/Daedra hybrid I think you're going to find is Lorkhan. Mankar Camoran insisted Lorkhan was a Daedric Prince, but Lorkhan conceived the mortal realm, and his body parts were used to bolster it as the Aedra either sacrificed themselves into the Earth Bones or fled, but whatever else he may have contributed was evidently removed from the world with his sundering. Not quite a Daedra, not quite an Aedra, but aspects of both.

Regarding the bolded, says who, though? Books can be (and in TES, often are) biased and/or incorrect. Bear in mind that even MK said that, while not confirming or denying either way, it is actually entirely possible Mankar was telling the truth. We can't say for certain that he was telling the truth, but we can't say for certain he was lying or just incorrect either.

Since when are Aedra associated with Anu and Daedra with Padomay?

Lorkhan is the Son of Sithis. He is also absolutely an Aedroth. In fact, he is the arch-Aedroth, as he invented the very concept of it.

Jyggalag is the Lord of Order.

Kyne sent a psychologically disturbed Terminator to Nirn to wipe out as much Merethic influence as possible.

Alduin ignored his mythic purpose and tried to take over the planet. None of these dudes fit neatly within their supposed "alignment".

But we can say for certain that he was more than a little bit nuts by the time the Champion of Cyrodiil reached him. He couldn't even get his Prince/Realm associations straight. That, and he was a pawn of a pawn of Hermaeus Mora. None of his ideas were unique and all of his boss's ideas (besides DESTROY) were copied from the Oghma Infinium. Not to say that Mehrunes the Razor isn't powerful; its just that his power lies in violently reshaping reality, not observing it.

The Lunar Lorkhan, Spirit of Nirn, God of Mortals, The Monomyth. Aedra and Daedra implies Lorkhan can be understood as one of the Aedra. I wouldn't dream of calling Mankar a liar, per se, but he could be as biased/incorrect as any of these sources. No reason to treat his word as gospel at the expense of all other information we have.

The ideas that he conceived the mortal realm and that he's a Daedric Prince are not mutually exclusive, by the way. I don't know if you meant to imply that, but he could've conceived the idea without actually contributing to it in the way the Time God & Co. did.