I don't even remotely agree.
Fanart can add, include or leave out whatever the artist likes.
There is no such thing as an "essence" of a character. There is simply an original depiction, no single part of which is central or integral when translating to another depiction.
What does and doesn't get lost in translation is entirely up to the artist, and whether they care to depict that given aspect.
I noticed this posts doesn't link back !neptunia@lemmy.world.
Cross-posts on Lemmy work by detecting whether someone has linked to the same thing, so to allow people to find their way to the original post, you can simply copy the image URL from your first post and re-use it any further posts instead of re-uploading the image.
Clients that support it will then show "also posted to" and link to the other communities to which something has been posted, allowing people to discover other communities they might like through the posts on communities they already sub to.