//------------------------------//
// Diagnosis - V 
// Story: Panacea 
// by AugieDog 
//------------------------------//

Both Pinkie and the princess went completely silent, but Pinkie was shaking her head. "What I do's a big, big secret, Twilight, and nopony but my subject can watch me work. That's built into the spell."

"I know." As much as Twilight hated it, this part of the answer was pretty obvious. "Except I've been your subject as well, haven't I? So I should be able to watch just fine."

"But—" Celestia had one front hoof drawn up to her chest, her eyes wide. "Why would you want to do such a thing?"

Pinkie's face showed just as much confusion. Twilight looked back and forth between the two and tried to find the words. "The Panacea spell is all about creating pain and suffering in order to feed the angry maw of the dark magic at the center of the world. But it's not just her subject's pain and suffering: it's Panacea's, too, when she's forced to torture and kill a pony she knows and cares about. It's the combination that gives the spell its power."

Princess Celestia looked like she'd been kicked in the stomach. "That...that's ghastly!"

Twilight forced herself to speak calmly. "Everything about this spell is ghastly. Like I said, that's what gives it its power: the more horror it generates, the better things go for the rest of Equestria."

"That's true," Panacea murmured, her listless mane and blank expression showing that she was once again slipping into control of Pinkie. "And that's why this last time was so strong, isn't it? Not just 'cause you're an alicorn, but also 'cause you're one of my very bestest friends." Panacea's grin stretched over her snout like a tangle of spiderwebs. "'Cause friendship is magic!"

"Then—" Celestia's snow-white hide somehow went pale.

"Yes." Examining her theory, Twilight felt that same thrill she always did when she'd finally cracked an especially thorny problem. "As the Princess of Friendship, if I force myself to watch the pony I love and respect more than any other in the world give herself to the knives of a pony who's one of my dearest friends—" She wanted a quill and parchment to do the calculations, but she still didn't have enough information and it really didn't matter in the long run. "The force we three create should be beyond the scope of anything this spell has ever generated."

The silence that settled over the room this time made Twilight think of a blanket of thistles. And when Princess Celestia said, "Very well," the barbs of those thistles tore every ounce of good feeling from Twilight's heart.

Celestia turned and started toward the table, and it took all Twilight's strength not to leap forward, get in her way, try to stop her. "Panacea?" she asked.

"Yes, Twilight?" came that breathy rumble from beside her.

"I don't suppose you have another set of restraints?" Watching Princess Celestia lay back on that metal surface and seeing the shiver that ran through her mentor when her warmth met that cold, cold steel, Twilight had to sit, her knees turning to jelly inside her. "Because when you start, I...I don't know if I'll be able to just sit here...."

"You have to," Panacea said, but Twilight couldn't look at her, couldn't look away from Celestia stretching her forelegs, her horn sparking to close the clamps around her fetlocks. "'Cause once I start, I don't stop. Not for anything."

"Yes, yes, yes." She'd spent at least two weeks in a futile search for cracks she could exploit in the conditional sections of the spell, so Twilight knew that Panacea was fully empowered to turn her knives against anypony who attempted to interrupt her duties. "I just—"

Two more clanks echoed through the room, Princess Celestia somehow squeezing herself onto Panacea's table and fastening the final straps into place. "Panacea," the princess said, and Twilight almost cried out when Celestia's voice broke. "I...I'm ready."

How the room got colder, Twilight had no idea, but when Panacea swayed up onto her hind legs, the magic that swirled everywhere made Twilight think the air itself had frozen. Then Panacea was touching her wall of knives, they were flashing and flowing to attach themselves to her hoofs, and—

The first stripe of blood welling from Princess Celestia's chest smacked Twilight hard, a molten copper and ozone stink that wrapped around her horn, too, the sheer wrongness of the magical release nearly knocking her over sideways. The sound as well, the swift clip-clip-clip of the blades digging into that pristine flesh—

And then the screaming began.

Twilight refused to remember that, though, pressing her face, crusty and sticky with dried tears, mucus, and sweat, into Celestia's heaving sides, the princess collapsed on Pinkie's bed after the second longest and most horrible hour Twilight had ever spent. Celestia's cuts were already sealing, her body knitting itself together much faster than Twilight's had, and the cyclone of magical energy that had at times threatened to tear out Twilight's mind and soul had settled to a slight rustling at the edges of her senses.

"Five years," a choking voice said, and Twilight pulled away enough to see Pinkie also curled up against Celestia, her face looking as wrecked as Twilight felt. "The power we summoned up, it should feed those grouchy guts who wanna kill all us ponies for five whole years. Maybe even six."

"Yes!" A fierce joy flooded through Twilight. She'd been right! Not about rebuilding the spell: it was such a mess, she was coming to think that might not even be possible. But by matching the spell power for power, friendship against death, she'd altered the balance, changed the playing field at least, and given her time to think of another approach. Dragging herself forward, she sprawled over Celestia's trembling foreleg and aimed her muzzle at the princess's ear. "Celestia! Did you hear? You've given us five years to find a more permanent answer!"

That Celestia's eyes were still clenched shut seemed odd to Twilight. She was breathing, though, and her lips were moving. Stretching, Twilight raised her head and heard, "My fault. My cowardice. Their deaths. All of it, all my fault..."

"What?" Twilight's skin prickled. "No! No, Celestia, you can't think that! You can't!"

"Can't?" Celestia's eyes snapped open, and the red fire that danced in them almost made Twilight leap away. "How can I not?" she shrieked. "All these years, all these centuries, I've sent ponies to their deaths at Panacea's blades when all it would've taken was an hour of agony on my part to save them!" A keening cry escaped her lips, and she slammed her head back into the wall behind Pinkie's bed. "I killed them all!"

"No!" Twilight jumped onto Celestia's chest and dug her front hoofs into the pastel jumble of her mane. "You didn't know! You couldn't have known! You and Luna, your special talents aren't magic, and Starswirl never understood the power of friendship! You three did what you could in terrible circumstances, and it's only right here and right now that we can see all the levels of the spell! That we can maybe figure out a way around it!"

Celestia was still panting, her eyes still closed, but at least she wasn't pounding her head against the wall. "My fault," she whispered again, though. "All my fault."

A different tack, then. "We can't wallow in it," Twilight said, trying to make her voice firm when all she wanted to do was wrap a hug around Celestia's neck and not let go till they both stopped whimpering. "Those who died, they're the real heroes of Equestria, and we need to remember them." She looked back at Pinkie, leaning against the wall and blinking her tear-crusty eyelids at Twilight. "Panacea knows all their names. We can set up a memorial to them now that—" She couldn't help swallowing against the lump rising in her throat. "Now that nopony will ever have to die again to power this spell."

Twilight was sure she heard a creak when Celestia opened her eyes this time, and she put on the gentlest smile that she could manage. A princess protects her ponies, after all, she thought, looking at Celestia's still unstable expression, and out loud she said, "You did what you felt was best at the time."

Her whole body quivering beneath Twilight, Celestia shook her head. "I can never forgive myself," she murmured. "If I'd been brave enough to give myself to Panacea at the beginning, we would've—"

"No." Twilight pressed a hoof softly against Celestia's lips. "We can't change the past: I've proven that at least once. All we can do is learn from our mistakes, vow to do better, and move on." Her throat threatened to close, but she pushed the words out anyway. "Can you do that much, Celestia? For me? Please?"

For an instant, Celestia froze, and Twilight found herself freezing, too. But then Celestia drew in a breath so big, Twilight, still sprawled across her chest, felt like she was riding a rising balloon. "I can try," she said, then she blew the breath out.

"Good enough." With a flex of her wings, Twilight sailed to the floor beside Pinkie's bed. "Now, we have five years. That gives us time to revise this spell, or if we can't, we'll see if we can't find out where this 'deep, dark magic' lives and pay it a little visit." She looked over her shoulder, both Celestia and Pinkie watching her, their manes starting to perk up. "We'll give it a choice: either it changes its ways and ends up friends with us like Discord, or it can keep acting the way it is now and end up like Tirek." She rubbed her face, itchy with dried tears and phlegm. "But first, I vote we get cleaned up a little."

"Ooo!" Pinkie sprang out from behind Celestia and landed on the carpet. "I'll bet Gummy's got the bathtub all full and soapy! He usually does!"

Celestia gave a gurgle that could've been a laugh and more tumbled than climbed out of bed, her legs wobbly but holding her upright, Twilight was glad to see. "Thank you, Pinkie," she said. "That sounds like exactly what we need."