…so before I saw the tags I was thinking why is Pinkie a shadowbolt?, then I saw she was dressed as the Mane-iac, and it made a lot more sense.

@Alara Rogers  

The only “forcible” parts about Rarity’s possession was after Nightmare entered her body, and it was initially when Rarity was having second thoughts, and when NMR was in Spike’s and Sweetie Belle’s presences. It wasn’t like Nightmare could just force it’s way into Rarity’s body and call it a day. Rarity had to have a negative quality that Nightmare could take advantage of, and use to establish and maintain its hold on her. And to establish such a hold, Rarity had to be broken to the point where she would accept Nightmare into her body. And Nightmare’s henchmen, Shadowfright and Jerome, did so by doing nothing more than simply talking to her.
 

Being bitten in the flank when a deal with the devil goes south will do that to the non-devil deal-maker. Especially if said deal with the devil involves loss of control over your own body, and witnessing firsthand what said devil is making your body do.
 

Which really doesn’t make sense without the very same comics that establishes that she was possessed by a demonic entity when she was Nightmare Moon. Because, if you ignore the comics, how would you even try to justify Luna punishing herself if she didn’t even get to do any damage beyond destroying at least parts of The Castle of the Two Sisters on the show, even against her will?
 

Before the Nightmare Rarity arc existed, yes. But even then, Lauren Faust did say that evil magic was involved with Luna’s transformation into Nightmare Moon. And when the Nightmare Rarity arc came to be, it pretty much explained where said evil magic came from. And afterwards? I would dare say that this scene provides such a suggestion. Especially when considering the way that the black mist seen engulfing her manifests, and Luna’s reaction when said black mist appears. (And it doesn’t take much figuring out to find out what that black mist is, for someone who’s read the comics.)
 

It’s just Jerome that acts comically. Everyone else behaved just like most other villains on the show.
 

You act as if Celestia could have freed Luna from Nightmare’s influence anytime she wanted to when it really wasn’t that simple. When Luna became Nightmare Moon, the Elements of Harmony lost half of their strength. And because of that, Celestia couldn’t exorcise Luna from Nightmare’s influence. She had to wait 1,000 years until the Elements of Harmony were able to find new wielders to use their full strength. Until then, she could only contain Nightmare Moon on the moon.
 
With that said, Nightmare try to turn Equestria’s citizens against Celestia, and tried to trick Celestia from undoing the seal the Elements of Harmony cast on it. With both plans enacted with the Nyx’s help. However, both plans backfired. And Nightmare decided to wait out the time by tormenting ponies in their dreams. Causing Nightmare Night to be invented.
 

“Undercut”? I don’t think there would be anything scarier, to be honest.
 

Considering stuff like what I said about “Do Princesses Dream of Magic Sheep?” not making sense without the comics, this is highly debatable.

@Background Pony #010E  
The story has Rarity being forcibly possessed – basically, being kidnapped and tormented until she weakens and is taken over. But in the show, Luna accepts Nightmare Moon’s crimes as her own. She created the Tantabus to punish herself. That hadn’t been made yet when the Nightmare Rarity story was written, but there was never anything in the series to suggest that Nightmare Moon was forced on Luna, or that Luna wasn’t ever really Nightmare Moon.
 
Also, the Nightmare Entities behave comedically, and the story involves Rarity being kidnapped to the moon, and Celestia and the Mane 6 traveling to the moon by pulling it close to Equestria. If it was that easy to get to the moon, why did Celestia wait a thousand years to retrieve her sister?
 
It’s a kid’s story, and it shows even more than the show in general does. They really undercut the whole horror aspect by having Rarity be possessed against her will. The show does these things much better; Rarity fell for the Inspiration Manifestation on her own, no forcible possession required. Plus, when you’re writing a comic about horrifying nightmare creatures possessing people, it maybe isn’t the best idea to have them act goofy. I think they were trying for a Bone homage, with the “stupid stupid rat creatures”, but… it really doesn’t work.
 
Gorgeous design for Nightmare Rarity, though.

@Alara Rogers: How is NMR’s arc “lame”?

Pinkie Mane-iac Pie is brilliant!

Sombrashy is pretty sweet.

Nightmare Rarity is always awesome. Even if the comic with her going Nightmare was kind of lame, the art was gorgeous.

i like the flim flam bros the most so applejack gets my vote but they’re all fantastic

They are so cute, it’s insulting to the bad guys…Except for Trixie. She’s already a cute pony.

Awwww, Rainbow looks so cute!

Fluttershy or Rarity.

That Jackie.

DiscoDash is just perfect!

All of them are awesome! But I love Trix-Twilight most!

These are all so good!

Probably Fluttershy, if only because the thought of her trying to be evil sounds absolutely adorable.