On this Tumblr Blog, the Dazzlings are given a different yet interesting backstory...

At first, they simply attack Twilight and her friends after brainwashing some Royal Guards;

However after a long battle with the Mane Six (and Sunset), the sirens are sealed away...

...but the Dazzlings turn out to be completely separate entities!

...and speak a different language... called Runic.

Translations:

Aria: Unicorn!
Sonata: Why is a Unicorn here?
Adagio: Don’t come closer! Run while I distract her!
Sonata: But-

(Wings…)


(Fine…)

Any now for their backstories:





(Runic)



(???)





Aria: An Earth Pony…
Sonata: I see.

We also see that they don't trust Unicorns.... at first...

And now, Adagio will explain Runic:

..and scene! So tell me, what are all of your thoughts on this backstory?

And yes, Adagio and Twilight are shipped in this story.

Hm. I think possessed-by-Pure-Evil has actually been done before, but the Dark Ages genocide going on is new.

I'm not all that fond of the Just Possessed angle, because it completely absolves the characters in question of everything they've ever been involved with post-possession (which is whenever the writer says it is) as well as their entire personalities. If they weren't themselves while we, the audience, were getting to know them, then we don't know the real them at all, effectively making them into OCs wearing the characters' skins when the spirit or whatever is exorcised. Almost sounds like they're possessed by whole new characters anyway, in that circumstance.

I've seen the idea of verbal magic before, too (Skyrim, anyone?), but it's no less an interesting concept.

And of course, I'm fully in favor of TwiDagio, even if I never find adequate reason to write it myself.

My personal headcannon has been somewhat similar. I'd thought the siren gems had something of their own personalities that sort-of possessed the Sirens. But more like the Symbiote from Spider-Man rather than full-on possession.

So, the characters still acted consciously, but their logic and reason were being suppressed slightly, while their greed and hostility were being magnified.

My opinion on possesed thing is simular to EyeSwirlsTheWeirded's but I just rather completelly despise it.