Fancy: Miss Rarity, lovely to see you this fine day.
 
Rarity: Lord Fancy Pants? How nice to see you again.
 
Fancy: Indeed, my lady.
 
Rarity: I must say, I’m not sure how to feel about this. You seem to always be here when I come by. Perhaps I should consider paying you considering how often you’re here.
 
Fancy: Never. I hate to impose. Besides, it can’t be helped. Fleur adores your dresses and I must accompany her to… advise her choice. N-not that your dresses aren’t amazing!
 
Fleur: (mutters) Please don’t drag me into this…
 
Rarity: I should hope so. How else am I to attract your sisters gaze?
 
Fancy: You need only enter a room and you’ll shine like the purest of gems… Your dresses I mean! T-they truly do shine and-
 
Fleur and Sassy: Just ask her out already!!
 

 
So I’ll be honest, I made this up on the spot. I’ve shipped Rare’s with Fancy for a long time but never could come up with a unique scenario. Though apparently, I can. Huzzaw!
 
Anyway, here’s some shipping between Fancy and Rarity. Post ‘suited for success’, Rarity left quite the impression of Fancy, making him go out of his way to try and bump into her. When Twilight came to Canterlot for the summit, he was greatly disappointed that Rarity hadn’t come with and had to make an excuse for meeting with her (My explanation for his behavior in Princess Spike). When she was in town, she was always working at her boutique and he couldn’t find an opportunity to see her outside the store. He had to use his sister, Fleur di Lis, as a cover to enter the store and talk to her. While she was very formal at first, Rarity began to look forward to his visits, though he kept insisting that he was only there to accompany his sister.
 
Fleur went along with this, though she thought her brother was being an idiot about the whole thing. Sassy was shipping them like crazy in her heart and was the one to break the tension by insisting they just ‘get on with it already’.