I like to think Rarity also is not as naturally beautiful as Sweetie Belle was when she was a filly. Rarity has to work hard to make herself look beautiful whereas Sweetie Belle just is.
 
I can imagine that Rarity might think Sweetie had everything handed to her on a silver platter while Rarity had to work hard even as a filly.
 
So for Rarity, it’s almost an insult to the hard work she puts into her appearance.

🎶Ooooooooooooooooh, jealousy…🎶

By limiting one’s sibling, limitation comes into the elder one’s life.
 
Yeah. The older one could learn from the younger one instead of being bitter jealous about it. Win-Win can be.

@Background Pony Number 17  
All that matters is which of the two gets Spike by the end

@Beau Skunky  
Well, Sweetie Belle is younger and less mature, obviously. And Rarity does like to hog the limelight; after all, she probably can’t fully get over her suspicions that Sweetie Belle is the one trying to steal it.
 
The two unicorn sisters have one of the best portrayals of “sibling rivalry” in children’s TV these days. It’s one of the reasons they’re my favorite pairing in the show.

@Background Pony Number 17  
Though, “For Whom the Sweetie Belle Toils” seems to imply Sweetie has more pent-up angst with her sister then vice-versa.

One of the things they never come out and say in the show, but is painfully obvious when you think about it, is Rarity’s serious case of jealousy toward her little sister.
 
Before Sweetie Belle came along, Rarity was an only child. And we’ve seen how Rarity operates on charm. She probably had her parents wrapped around her hoof from the day she was born.
 
Then comes Sweetie Belle, and not only is Rarity no longer Mother and Father’s only darling, little sister is doing the “charm” act. Rarity’s charm act. And to make it worse, being younger and cuter, she’s doing it better. It’s no wonder Rarity moved out of the house as soon as she was old enough to live on her own.
 
There’s a reason a lot of fanfics and comics have Rarity plotting to murder Sweetie Belle. In her darkest moments, the thought has probably crossed her mind.

@G.S.  
Variety’s the spice of life, mate.

@G.S.  
Yeah, complete opposite for some here…

I’m from the future. She will become equestrias most beautiful mare Rarity, stop her now!
 

@DanielTepesKraus
 
S’not our fault we’re attracted to human body shapes more than equine body shapes.
 
Well.
 
Most of us are.

She’s working on it >>624627

@Beau Skunky  
HSSSSSSSSSSS! All anthro!

@Beau Skunky  
Apparently when Sweetie Belle grows up she’s going to turn into an anthro mare xD

Y’know, she has a right to be paranoid about that, if pics like these are any indication of what the future holds. >>454873 >>623239 >>388327 >>355336

“You are not the first one Sweetie Belle. Have you even entered the basement?”

Too late.