"Indeed. As with all tools, it has its purposes."

She nods, humming, turning over what her Mistress said, what she remembers from Anakin's lessons... "Okay. Where do I begin?"

"First, a demonstration." She holds out a hand. "Break one of my fingers."

...She does not want to hurt her Mistress but she was ordered. 

Darth Sangua settles into - she is her Mistress's will, and her Mistress wills -

She uses the Force. A clean break, right through the middle of the first bone of her Mistress's ring finger. 

She hisses slightly in pain.

"Now, observe closely." She focuses, reaching out to tap the swirling currents of the Force. A purple haze develops around the first two fingers of her other hand. Once it's gathered, she directs it to her broken finger with a sharp gesture and the energy leaps over to envelop it, sinking in to rapidly reknit the bone.

(...It makes something smooth and vicious curl in Sangua's chest to have gotten a visible reaction like that out of her Mistress.)

She does observe, gaze focused, brow furrowed, and starts pointing out technique differences from Jedi healing.

Of which there are several, yes. It is important to have a solid grasp on the theory before trying for oneself, so Sidious will make sure Sangua fully understands through discussion. And a few demonstrations with Sangua on the receiving end.

She has far fewer conflicting emotions about being demonstrated on! It feels nice, actually, in a different way than being tortured for her Mistress's pleasure. This is for a lesson, to learn a practical skill - to hone her as a weapon.

She's a very attentive student, and it's quickly obvious why she's consistently at the top of classes containing even full Jedi Knights. Sangua assimilates information rapidly, gaining a thorough grasp of the theory and dipping her toes into speculation on what's past these basics by the end of the lecture, the pain only pushing her mind to a sharper point. 

Sidious approves of her quick-witted apprentice.

Smug grin.

"Am I ready to try it myself, Mistress?"

"Carefully, and under supervision, yes."

"Alright."

"On myself, then?"

"Yes."

She hums. "Okay... I'm ready to start."

And she holds out her left hand in front of her, breaking the tip of her ring finger - another very clean, simple break. 

Then... Focus her will... She cuts out everything from her perception except the Force, the command she's giving, to knit bone back together - 

It goes, but-

-How much bone does she need to repair? All the bone? There's this lovely little gap just a little further back that could be filled up. And perhaps she might add more bone all around, to really thicken things up, make them solid, unable to break again. It would be safe like that, she need fear no more hurt.

Nope! Nuh-uh. 

She likes that gap. It's useful. She likes the ability to break when needed, likes the pain, the flexibility is important. 

Those are facts she knows. Bedrock behind her thoughts. 

Darth Sangua doesn't bother communicating the why. She just presses her will on the Force. No. That is not what I commanded. Do as you are told. 

The Force does as it is told.

"Well done," says Sidious.

Grin. "Thank you, ma'am." She flexes her hand, feels her finger - feels good. 

She takes Sangua's hand and kisses the recently-broken finger.

Feels very good now. Sangua giggles. "Should I practice more, Mistress?"

"One or two more times now, certainly. But never on your own, until I give permission."

Serious nod. "Yes, ma'am; I'll try to use the Jedi version in any emergencies, too, at least until you clear me otherwise..."

She can have a kiss for her obedience. "Now, again."

Shiver.

She breaks another bone - a slightly more complicated fracture this time, though still on a finger bone she won't miss if it gets screwed up. And... Again.