Sister Struggle- Smother (Patreon)

Given their position (and how dominant Mileena's is, in particular), there's an easy answer here: Smother her out! Not only is true asphyxia a world of agony comparable to some of the worst torture you can imagine, its probably the single most humiliating way to go out. Added bonus: Mileena's outfit might as well have been perfectly purpose-built for it!

Mileena uses the leverage from her legs wrapped around Skarlet's torso to thrust down with her hips, forcing her sister down to the ground on her back. Skarlet is still fully able to bridge and writhe, but it's taking her much more energy to fight back than it is for Mileena to keep her held down. Eventually, her struggles start to wane. The opportunity comes for Mileena to make her move.

In a quick movement, she launches herself forward along her victim's body- moving her hips well up past Skarlet's waist and putting her weight much further up near the helpless sister's chest. From there, it's a simple matter of using her arms to pin Skarlet's down and laying her ample chest across Skarlet's face. With the window available in her costume, her victim's face is immediately and completely enveloped. Panic sets in quickly as Skarlet realizes what's happening, but already starting to tire there seems to be little she can do...