Sibling headcanons, other continuities, and more (The incest debate)

So I saw a recent image that got be thinking, and not because of the image itself, but because of the tags.  

 
As far as I’m aware, these two are never referred to as related in any official media, yet it is a very popular and common headcanon. But does that mean that every image of them interaction counts as siblings, or in the case of romance, incest? Or should it only apply when the artist intends it?
 
A slightly similar case is The Dazzlings, referred to as sisters in the IDW comics, but not mentioned in the EQG movies or series. Since not everyone reads the comics or cares to follow their continuity, many artists ignore this or never even heard it and have been drawing and shipping them as unrelated for years, so as far as I’m aware, we don’t tag any of those as siblings or incest unless the artists intends it.
 
The latter may be canon but it’s tagged probably less than the headcanon before it, and that has me wondering how all of these should be handled. Another couple popular sibling headcanons are for Sunburst and Sunset, and Dinky Hooves and Amethyst Star. Interactions and/or shipping between them could count as either (do people ship the latter?!?) depending on what the artist intends, popularity tho sometimes makes people want to make non-sibling intended images as such, or the other way around.
 
So, basically, I think headcanons and other continuity mentions of relations could use some refining on clarity for them for tagging purposes. Personally for both of them I think that it should only be tagged as such if the artist intended it, which is PROBABLY mostly how it is tagged for all of them (not just the ones I named) but I’m sure some slip through the cracks.
 
Thoughts?

I do agree that artist intent should be considered over show canon when it comes to art pieces. The thing you have to think about is general knowledge of canon, and perception or interpretation of said canon.
 
For example, a lot of (if not most) people don’t read the IDW comics, and the IDW comics are overridden by show canon all the time, so most people take any canon established in them as dubious at best. Scarcely anyone references them even when the comics are well-liked, so amongst the general fandom and the artist community any canon established in them basically doesn’t exist. So the Sirens being sisters in them essentially means nothing to your average person, even if they know about it. It’s likely to be dismissed out of hand purely because the comics don’t mean anything to them.
 
As for the whole Flitter and Cloudchaser being sisters thing, that’s a different beast. They were never named as sisters, true, but the fandom accepted the idea so quickly and thoroughly based on their designs alone that nowadays to anyone on the outside it would be natural to assume that they’re siblings in canon, largely because there’s so much fanart of it. I wouldn’t be surprised if many artists who’ve drawn them either didn’t realize they were never siblings in the episodes they appeared in or never watched most of the episodes they were in in the first place. It’s such a normal perception of them at this point that I think it’d be hard to argue that any artist that drew them nowadays wouldn’t consider them siblings if they didn’t explicitly mention otherwise.
 
In the end, this whole thing circles back around to the first statement: Artist intent matters first and foremost when it comes to these things. However, artists will often not state their intent or will assume things with any real investigation.
 
So perhaps we should consider tagging things on a basis of what is considered the average interpretation, unless it is stated otherwise. Otherwise investigation is required, which may be a bit of a mess considering the sheer number of artists involved. Taking into account the fetishes and personal leanings of particular artists is a given I would think. Most tend to stick to what interests them.
 
I think what we have now works more or less, despite its inaccuracies. If you have more concrete ideas for improvements it would be interesting to hear, though.

@Napsack  
I think that even if in the end nothing changes, all the conventions for it as of now should at the very least be written down (on the siblings and incest tags) just so new people can figure it out. I’m not sure how to do that yet but it’s my main goal!

@LightningBolt  
That’s a good idea, if nothing else changes.
 
There’s a surprising amount of history you have to know to understand these things. It’s weird, and it could definitely do with some clarification for the future. If you need to discuss ideas on how to write all that out then bouncing concepts back and forth in the thread wouldn’t be a bad idea.

@LightningBolt  
I don’t think pegacest should imply incest, though the name can stay. The description alludes to the fact that while they aren’t explicitly sisters in canon, it’s a common headcanon. Still, we shouldn’t base implications on headcanon, so it should be left to uploaders to tag it as incest where applicable.
 
polydazzlings is weird because comics are in a gray area in terms of canon. It’s official content, but lots of stuff in the comics has been rendered non-canon by the show, so does that nullify the rest of it? Here, I’d defer to fan opinion, which is generally that they’re not sisters. The implications can be left as-is.

As a general rule, canon sets a baseline for expectations, but it’s not the end of things. What’s in the image matters most, and what the artist looks to be trying for matters a lot; this applies to a lot of things, like whether a certain bump is a sheath, or whether a character is dead.