Literally rape her mouth into the max. Only on mouth

Complex Gags. INCREDIBLE!

Oh come on, the ring goes in the teeth to hold the mouth open! The ring in a ring gag doesn’t sit on the lips, it would make it useless.

@Background Pony #B1FE  
HAHAHA that’s a good one lol

Rare is such a sucker for BDSM. Just look at that face - she NEEDS you to stick it in.

@Background Pony #B3AC  
For Fluttershy I could see her being into pet play actually!

I believe your estimate of Rarity’s personality and sexual quirks is probably right on.
 
Twilight Sparkle, Rainbow Dash, Fluttershy: awkward virgins  
Pinkie Pie: too childlike to sexualize at all  
Applejack: sexually experienced–but probably not into any of that weird big-city stuff, enthusiastic but not sophisticated  
Rarity: experienced, kinky, playful, can switch between Domme (“Bend over, Darling”) and sub roles with aplomb, probably a hell of a lay and lots of fun in bed

@Setsugekka
 
See! someone finally agrees!

Nice face harness :3
 
Agreeing with Rarity being most likely into BDSM!