What are her options here. Her options don't look great, to be honest.
"...very helpful, thank you."
She tries... moving the thing around. Such as for example back into her body, that seems like a good place for it to be.
"Well, you want to become strong, don't you? Everyone wants to become strong. But right now you're weak. Your soul's fragile and dull. I can help it to grow stronger by giving you some Love! Down here, Love is shared through these..." He waves a frond, and several glowing orbs appear around him. "Little white... 'friendliness pellets.'"
They float towards her soul lazily. "Try to catch them all!"
Sable has never been more tempted to ground-rip an arguably living being in all twelve years of her life.
But no matter how desperately suspicious the creature, she has no way of getting her apparently vitally important soul back without playing its horrible game.
So she braces herself and bonks the heart gently against a pellet.
The collision before felt bad.
This feels like a blunt, serrated, rusty knife being driven through her spine. She's left hanging on to life by her teeth and nails.
Flowey's adorable little face twists into a hideous grin. "You IDIOT. Did you really think someone would help you, down here? In this world it's kill or be killed."
In the distance, there's the sound of paws running towards her. Flowey looks to be too busy cackling to notice.
She reaches out with groundsense and takes hold of this horrible little creature's horrible little life-essence and pulls as hard as she can. Which is very.
And the owner of the paws careens into the room.
She looks like something between a woman and a goat and a very sleek bear, and she is enormous. Sable's father standing next to her would look shorter than Sable herself looks standing next to him. And, incidentally, her paw-hand cups a magnesium-bright ball of fire.
The fire dissipates when she sees Sable. "I thought I heard-"
She stops in her tracks. Her eyes go distant. "Chara?"
"Who the blight is Chara?!" gasps Sable. She feels less like death now that the flower-thing's brilliant ground is being absorbed into her own, but this restorative comes with its own complications, namely an all-consuming agony as her damaged ground fails to reconcile with the foreign material.
"I-"
She shakes her head. "My adoptive daughter. She died. You look like her. Sorry."
She looks sharply at Sable's soul. "Who did this," she snarls, and makes a complex motion with her hands.
Energy suffuses Sable, mending her spiritual wounds and brightening her soul until it shines again. Her ground feels soothed.
"Some sort of... flower... creature," she says, gesturing vaguely at the pile of petals. "Um. Thank you? What did you do? What is happening?"
"You're welcome," she says, returning to her usual clipped tones. "I healed you. It's not very difficult. 'What is happening' is a broad subject, but currently relevant is that you are the first human to fall here for multiple centuries, you obviously had no idea that monsters even existed, and that you look exactly like my deceased adoptive daughter, which is moderately distressing. In light of this I would like you to accompany me to my home so that I can protect you from harm."
"...that... sounds like a better idea than waiting here for another horrible flower creature to attack me, admittedly... I'm sorry about your daughter."
"It has been several thousand years. I have had time to adjust."
She looks at Sable's comparatively short legs. "Would you like to ride on my shoulders? I suspect that I walk faster than you."
"...that would be... okay, but um, what do I do about my, this," and she gestures at her glowing red light of upsetting vulnerability.
"...Oh. You're new to this. It will follow you without collision if you don't concentrate on moving it."
She hefts Sable gently and places her on one of her massive shoulders. Reaching into a pocket, she pulls out some kind of candy wrapped in rice paper. "Have some candy. It tastes good and is generally soothing to traumatized children."