What is it about this particular ship that attracts you?

I guess first and foremost those two are more or less my favourite characters (Celestia ranks pretty high too, but shipping her seems a lot harder). And it's pretty inevitable you would want to ship your favourites right?

Why do I like them? I always enjoyed the fine line Rarity walks. She is very ambitious and self-centred and yet remains the element of generosity. These are aspects of her personality that are almost contradictory, and yet she manages to balance them out in a realistic personality.

An awesome episode where this comes through is the one where she becomes part of Canterlot high society. There she is, living the dream, and yet constantly thinking about Twi and the great gift she wants to make for her for the minor favour she did for her, but constantly getting sidetracked...

And then when all the lies caught up with her we expect the whole situation to blow on her face and a harsh lesson about generosity to be learned...but that never happens. Rarity failed to live up to the great ideal of generosity she is the physical embodiment off...and that is ok. Because elements of harmony aside, she is only hum...a pony.

As for Pinkie, well, I think that one is basically self explanatory. In between the excess of energy, the randomness and the blatant cartoon physics/breaking the 4th wall, what is there not to love? Though I do feel it's important to point out that behind all of that there is a real person, as sometimes the fandom tends to somewhat exaggerate her eccentricities in such a way that swallows up her whole personality (though admittedly that tends to happen mostly in stories where she is a secondary character and tends to only be noticed when doing one of her antics, still some people could go a little easier on the "pinkie knows this is a fanfic comments").

As for why they work together. Well, in fiction at least, the best couples are often those who have a lot in common, but also fit the "opposites attract" description, for as long as those don't cause an excess of friction between them.

I dunno if Rarity and Pinkie are the two characters that fill that requirement the best, but they do fill it.

The opposites is obvious: Rarity the composed proper one, Pinkie being pretty much the embodiment of chaos were not for Discord claiming the title (although if you compare Rarity's workshop and Pinkie's kitchen...).
As for the similarities: When you consider their elements and professions, you realize that more than any of the others Pinkie and Rarity derive satisfaction and personal validation from making other people happy. Rarity with her dressmaking skills (but decorative as well) and Pinkie with her parties.

1253080 Well, for me it was initially inspired by how well they meshed in scenes I wrote them in. Rarity makes the perfect straight man to react to Pinkie's antics. You tend to notice when two characters have good chemistry. As a matter of fact... when I began writing Smile I actually found their chemistry as lovers was spilling over into my Flarity story, Green. I had to stop writing Green until I had resolved things with Pinkie and Rarity somewhat.

1253080
I'm quite a fan of opposites attract as evidenced by my love for Flutterdash, so that's one reason. That said, I believe that their personalities can mesh well despite having very different behaviors. I can see them liking each other for that. Rarity might admire Pinkie Pie for having so much energy and being so keen on keeping everypony optimistic and cheerful. And the other way around, Pinkie Pie probably would admire Rarity for her passion in what she loves and her generous spirit.

I like your points though. They seem pretty valid.

Mostly because of Pinkie, but also I wanted to see more interaction between the two of them

1253080 I've always felt "opposites attract" is an over-simplified way to look at characters' differences. You could make an opposites argument for just about any Pinkie ship, possibly excluding Pinkie Dash. What matters is not how different or similar they are, but rather how their similarities and differences mix. Chemistry, like Steel Resolve said.

Rarity and Pinkie have excellent chemistry. Their differing ideas on what is and is not an acceptable level of messiness contrasts nicely with their shared compulsion to do things to make others around them happy. Their different levels of exuberance is countered by the fact that they can both be large hams on occasion.

But probably the main reason I like RariPie is simply that I really enjoy seeing Rarity get to loosen up and have fun.

1253209
That is an interesting response. I guess it makes sense one would learn about the characters as one writes them. And way to self-promote you sly fox

1253947

I've always felt "opposites attract" is an over-simplified way to look at characters' differences. You could make an opposites argument for just about any Pinkie ship, possibly excluding Pinkie Dash. What matters is not how different or similar they are, but rather how their similarities and differences mix. Chemistry, like Steel Resolve said.

Hummm...I wanted to leave something for you guys to say?

Well, for one thing pink looks good on white. But that is not the main reason why this is my personal favourite ship.
They are certainly not alike, yet they share many qualities, especially their main motivation, helping other ponies by making them beautiful or happy. This sets them apart from the rest of the Mane 6, as their main motivation seem to lie elsewhere (knowledge, family, self-aggrandizement, caring for animals).
There is no need to suspend disbelief that these two could get along well as evidenced most clearly by Putting Your Hoof Down. They seek each others' company, they can work together (at least at Sugarcube Corner–the Carousel Boutique might be more… challenging), and they can address problems together.
Donny's Boy summed up my attraction to the couple very nicely in Seeking Beauty, where the characters state that what attracted them to each other was that one saw the world and how it could be made beautiful, and the other saw the world and found it beautiful. Such two minds would supplement each other well.
They are also ponies who can help each other. Rarity to become a bit more relaxed, and Pinkie to become more focused. Their shared need to help other ponies lie, I believe, also in their shared weakness or fear, namely the rejection or abandonment by others (as explored in, e.g., Party of One, or the Nightmarity comic book arc). Pinkie fears being alone, Rarity fears being rejected, but together they would be strong.

Everyone said a lot of what I might've said (except way better than I would've said it), especially Steel Resolve and Esle Ynopemos, so I'm gonna just be shallow and silly:

Pinkie put on a tux for Rarity. That is adorable.

I first noticed them as a pair the first time I watched Over the Barrel, when Pinkie jumped off AJ's wagon. Other than it's hilarious, I kept wondering why Pinkie picked Rarity to catch her. That's when I started lurking this group, then reading up on fics, and then noticing their adorable little interactions sprinkled all over the seasons when I started rewatching.

Also, Rarity's destiny is A ROCK. Pinkie came from a rock farm.

Well, everyone else has already gone on about their great chemistry and stuff, so I'll just say the real reason why I ship them: their canon friendship. There are so many great moments in the show (especially Putting Your Hoof Down) which just shows them being so great together, not getting annoyed with each other, staying true to themselves, balancing out their difference. And not to mention it's always hilarious. Besides, it's cute.

I know it's off topic, but I have a slogan for RariPie:

"You're never fully dressed without a smile."

I saw Annie today so yeah.

They remind me of Lucy and ethyl. They make the perfect comedic duo. Plus they're cute together, I like how they interact.