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Should Nanika have her own entry? She is undeniably a separate entity from Alluka given new information, and so tropes that are being attributed to Alluka should really be Nanika's. It seems like she should be considered a spoiler character and/or maybe a sub-folder under Alluka's.
Is there really that much separate information about Nanika to warrant a different entry? The story basically gave no hints about either Alluka or Nanika before they were introduced. Alluka and Nanika have both pretty little development on their own other than being unwaivingly loyal to Killua.
At this moment, the story has actually veered away from Killua and is focusing more on Leorio and Kurapika. Up until there is actually more information on Nanika and Alluka, the entry should remain the same in my opinion.
This is potentially spoilers, but information from volume 33 confirms that Nanika is not Alluka's nen ability and that she's a being from the Dark Continent. She's a different being and a different character from Alluka, so the fact that tropes that only apply to her + her powers are listed as Alluka's is a bit of an issue. I recognize that the reveal of them being two different beings (which is sort of an underlying theme of the Election arc, even there was still minor reasonable doubt as to whether Nanika was a nen construct or not until a few days ago) is a minor spoiler, but it's also one that's really important.
However, I think it could very easily be made into a sub-category in a way that keeps that reveal a little more under-wraps, and that would be "Tropes related to Alluka's powers", with the details about Nanika specifically spoiler-tagged.
The gist of it is, Nanika and Alluka are not the same character, so while I'm not opposed to having them share an entry I think it's straight-up inaccurate to just leave these tropes all under an entry that's purportedly just about Alluka.
When you put it that way, it makes sense. Still, the Dark Continent link to Nanika has been implied and not quite confirmed as far as I remember. I would appreciate if you point me to this fact, if indeed it is, as I have only read the scanlations available online and there has been no further information from the Dark Continent arc since August 2014. I might be wrong.
What I mean is that I'm open to the separation should there be more information.
NVM man. I just realized that there's new chapters. It's been so long that I gave up on checking periodically
For the record, the information re: Nanika is revealed exclusively in a bonus extra added in the recent release of volume 33 and not in a recent chapter. It's a single image  of Nanika seen between chapters 341 and 342, accompanied by her "aye" catchphrase and the text "暗黒大陸 出身です (essentially, "I'm from the Dark Continent") ." Warning that it's a slightly unsettling picture.
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How well does it match the trope?