-Regna Ferox, Undisclosed Location-

"That is a terrible plan."

"Robin," Emmeryn looked troubled, deeply so. "Is this truly the only way you can think of resolving the situation?"

"Only way? No," Robin shook his head. "But it's the only way that I estimate has anything close to a reasonable chance of working. Certainly, there are other options, however, they bear … slim chances of working, or else drastic measures such that they risk the rather precarious stability that currently exists."

"Drastic measures?" Emmeryn raised an eyebrow. "Robin, considering what you've just suggested, I do not know how you would be able to call anything beyond that to be a 'drastic measure'!"

Robin had spent the last ninety minutes outlining a plan to the two of them. It had started with what Robin believed to be the correct response to what would undoubtedly be Valm's second wave to attempt to force an uneasy alliance between the three countries, whether they wanted to or not. Afterwards, Robin had continued, going through stages of the war and finally what he considered to be the ultimate endgame of what their plans should be.

His recommendation was, as Emmeryn had noted, incredibly drastic. Robin had given an estimation that the fighting strength of all three countries would be depleted by half, at minimum, and several large swaths would be thoroughly ravaged by war. There would be months of attrition, some incredibly risky maneuvers, and significant sacrifices that were required to be made.

"You would be surprised, Emmeryn," Robin said, easily. He looked up. "I suspect you may have considered one or two of them yourself. Basilio certainly has."

"Assassination of all three of them?" Basilio said. Robin nodded. Basilio shook his head. "It would never work. We'd be exposed, and even if we weren't, there'd be too much suspicion as a fallout to have any degree of cooperation."

"Yes, but there are ways around it," Robin said. "Certain … narratives … could be crafted, for instance, which would help expedite certain matters. And assassination isn't need, mere incapacitation is enough."

"So you have considered it in detail," Basilio grunted.

"Certainly. Flavia's right arm would be sufficient, I think," Robin said. "It would not be difficult to have her cede the majority of her acting authority to you after that. Asculum would suffer a relapse from the curse to debilitate him, forcing you, Emmeryn, to step up. As for my father…"

Robin felt his throat constrict. He braced himself and forced through it.

"…I might not have a choice in the matter," Robin spat. "There are … magics … that can bind blood relatives by another's will. Validar swore to never use one to force me to his will, something he did as a sign of trust in me. But I've made no such oath."

"It seems you have placed a great deal of thought into this," Emmeryn said. "And you think that this will not give us the best chance at victory?"

"As Basilio said, even with the best of intentions, there would be problems with all these methods," Robin said. "Repercussions – in this case, a delayed rise in insurgents over all our nations. They might be mitigated with the proper narratives, but that would have repercussions of its own."

"When you say 'narrative'…" Emmeryn said, slowly.

"At minimum, engagement to one of us," Robin indicated to either himself or Basilio. "Though stronger steps would be required. It would likely be me. Likely married. Likely with heir on the way."

"Ah," Emmeryn said softly, and closed her eyes.

"You weren't kidding when you said, 'drastic measures'," Basilio said.

"If such is what it takes, I would do it without hesitation," Emmeryn said. She looked at Robin, her piercing eyes meeting his. "You know this. There is no sacrifice I would not make for the sake of Yli- no. There is no sacrifice I would not make for this continent, Plegia included. It is time for me to stop thinking of my citizens as any different from yours."

"I know, Emmeryn," Robin said. "I hope it doesn't come to that. Like I said, there would be repercussions if it came out that there was a union between Plegian and Ylissean royalty. Revolts, most likely. Even if it meant unification against Valm, that's meaningless if the continent falls to chaos anyway. Still, if I had to choose between collapsing now or collapsing in twenty years…"

"There is hope in one of those two options," Emmeryn said. "And this is why you've outlined your current plan? You believe this gives us the best chance to succeed?"

"Yes. Though, obviously, it is not without sacrifice," Robin said. "Likely, before this is over, two of us present will be dead."

"Charming thought," Basilio rumbled.

"Any sacrifice is worth the cost."

"Glad to hear you say that, princess," Robin said. "…So, anyone have a spy I can borrow? Or well, like a dozen of them? I need to get started on my part. You two need to figure out how to get Ylissean troops to Regna Ferox in time for the second wave."

-Castle Plegia-

"How many plans have you made in my absence?" Validar asked.

Robin contemplated lying, but it likely wasn't worth it.

"One. But it's a pretty big one."

"Anything to do with the Gemstones, like I requested?"

"If it goes well, I should have them all," Robin said. As it happened, Gaius and Panne were stationed by the arena, ready to swipe the Gemstone there once given the opportunity, which Robin was sure would happen during the chaos. "I've heard a rumor that some of them might have been moved overseas to Valm, though."

"Have you? Interesting," Validar said. "So I presume that you'll interfere with the invasion on that rumor alone?"

"If I deem it necessary," Robin replied, keeping his face straight.

Validar laughed at that. "Oh, you truly are one-of-a-kind, my son. Very well, continue on with your games. But make sure you do locate those Gemstones as fast as you can."

"I may require some of the more specialized tools at our disposal," Robin said. "That won't be a problem, will it?"

"I will need to be apprised beforehand, but it should not be."

"And I'll need my sister back. Long-term assignment," Robin said. "I need our Mistress of Spies."

Validar considered. He shook his head. "No. I shall need her help keeping tabs on the other armies within the continent. Ylisse has, unsurprisingly, decided against helping anyone and Flavia is guarding her own border. Information is at a high premium, and I need as much of it as possible."

"Father, I need her!"

"You have no one else?" Validar said. "You have acolytes, you have spies, you have thieves. Aversa is my asset, Robin, not yours. I told you to train the new woman of yours for this role."

"Thrall is unsuited for the role as spymaster, but she's inspirational and has natural charisma. Thrall is perfect in her role all a folk hero for the masses. Aversa is the best spy we have," Robin said. "Father, I need her, there's a role only she can fill."

"As do I. You've made do without her before, you'll do so again."

Robin grit his teeth.

"I know tensions have been high, but that's all the more reason to listen to me," Validar said.

"…Can I assume that our primary point of defense will be Carrion Isle?"

"Didn't I assign you to find the Gemstones?"

"Do you have anyone else who can command the defenses?" Robin countered. "I'll just move my resources there and prepare the defenses while I work. Do you have any plan beyond that, or did the summit go so sour none exists?"

"I'm sure you know how well the summit went."

"…Yes," Robin saw no point in lying.

"Then you know that Asculum has decided against the rational path forward, unsurprising, but I have no plan. I will have one, though," Validar said. "Hmm. Very well. I shall allow you to take Carrion Isle."

"Good. I'll need Henry for this," Robin said. He slowly rose to his feet and turned around, slowly walking out. He walked out of the throne room, and noted Aversa following him with amusement, seemingly coming from nowhere. Robin nodded to her and then turned to walk towards his quarters. Aversa followed him, smiling with amusement.

"So…" Aversa began. "Haven't seen you in a while. But you're not surprised that I'm here and following you."

"Because I'm not. It is very good to see you, Aversa," Robin said. "But I'm afraid that we may not have time for pleasantries."

"You have a favor to ask of me, don't you?" Aversa smiled. "Something that daddy dearest wouldn't like?"

"Yes."

"You know I'm loyal to Validar over you, right?"

"I saved your life, sister," Robin said.

"Yes. But you didn't raise me as a child," Aversa said. "My familial allegiance to you is not as strong as Validar. And just because you saved my life doesn't make me enthralled to you. That's your girlfriend. Besides, I'm family. You have to save my life."

"You weren't family yet when I did it!"

"I was always your sister, you just hadn't realized it yet."

Robin decided against trying to puzzle through her twisted logic and just continue. "I have a plan,"

"I'm shocked. Truly, I am," Aversa sighed. "This plan of yours. Risky? Suicidal? Little to no chance of success and hinging on ludicrous chances?"

"I wouldn't phrase it like that…"

"So, that would be a yes."

Robin sighed. "Yes, Aversa. Dramatic results necessitate dramatic risks. And Father is being too stubborn for his own good. I have a plan that could secure the continent. But in hinges on a few factors."

"Such as?"

"Cooperation between all three countries-"

Aversa snorted loudly.

"Among other things," Robin trailed off. "Okay. I may have lied about the cooperation between the countries part, I just need … I need a spy. One spy, can't risk anymore. And I need the best one possible."

"And that's me?"

"It's hard to say," Robin turned to her, stopping in front of the door to his wing of the palace. "The nature of spies is such that the better they are, the less you've heard about them. As far as I know, Basilio is his own best spy and while Ylisse doesn't use them in general, House Themis does make use of them, but I believe you're the best on the continent."

"Oh? Just this one?"

"Well," Robin opened the door behind him and stepped inside. He nodded, and Aversa smiled, stepping in. Robin closed the door, and it pulses once with dark energy. "I intend to find out."

"You're only shutting off the conversation now?"

"I don't think Validar would be spying on me," Robin said. "But even if he did, I'm notoriously stubborn and I'd probably pester you into listening to me."

"You don't about him knowing you asked me to spy for you anyway. But you care about the what."

"Exactly. I need a spy across the ocean," Robin said. "We don't have sufficient intelligence on our enemies. And I need that."

"Validar wants me to keep tabs on internal troop movements."

"Important," Robin paused. "But I have a way of doing that."

"So why don't you just – oh. You can't let Validar know how you're getting that information," Aversa said. "So, who are you working with? Basilio? Yes, likely. He's a very practical man. But that's just one dance partner. And you need a full card, Robin. Who else do you have lined up for this?"

Oh, this is how Chrom felt when I cold-read him, isn't it? Robin flinched. This feels bad from the other end.

"Not Emmeryn?" Aversa's eyes sparkled. "Hmm, I heard a little birdy whisper that she disappeared from Castle Ylisse a while back, when you and Thrall disappeared from here as well. Just long enough for … say … a journey to and back from the Longfort."

"You are a very capable spy."

"And you haven't answered my question. Who are you working with? Are you going to answer that?"

Robin considered. "Do you want me to? I'm guessing you don't."

"I don't need answers that I already know," Aversa acknowledged. "So, what's the plan?"

"The plan is that I need your help."

"I need to help Validar," Aversa said. "But I can give you everything possible in my power outside it."

"I have a feeling it might be more than that once you hear my plan."

"Maybe. But that's only one part of my request," Aversa said. "There's something else I want."

Robin felt a chill down go his spine. Uh-oh. She never does this.

"Propose to Lissa."

Robin blinked.

"I don't want to hear anything about how marriage is a political tool," Aversa said. "It is, but if you cared about that, you'd have cut her off at the start and arranged for her to be your sole mistress, which you haven't. Not to mention that you've set no long term plans about using anyone on the continent for political marriage. You're just being a coward about it."

"I'm not being a-" Robin stopped short and scowled. "This is none of your business. And you don't even like her, do you?"

"I probably wouldn't be friends with her, but fortunately, she's my sister-in-law, so I don't have to," Aversa smiled. "It's for your own good, Robin as well. Don't forget that."

"The situation is too complicated for that! Besides, we're in the middle of a war right now!"

"We won't be once this is over."

"…" Robin silently glared at her as he considered calling her bluff.

"Well?" Aversa smiled.

"I'll ask. I make no guarantees for her answer," Robin responded. "And if you weren't my sister, I'd… I'd do something, I'd assure you."

"Good. So, what's your plan?"

"Well, the first step is that I need you on Carrion Isle when Valm attacks it. We have maybe three months at most."

"You think they're going to attack Carrion Isle?"

"Not by their choice. I've already arranged for deserters and turncoats to be sent across the ocean to Valm. They're real enough, but the confederates that arranged the trips were mine. They'll probably be executed by Valm anyway, given that Valm won't trust them, but the ships will have maps, and I've rigged the maps to have Carrion Isle look like a tempting staging area for an assault on Plegia."

"One step ahead, huh?" Aversa chuckled.

"Always," Robin said. "Without it – well, I wouldn't be me, now would I?"

"What makes you think they'll attack Plegia? They only attacked Feroxi last time."

"They didn't come in force last time," Robin countered. "And they'll come after us by ocean eventually. Supply lines across the Feroxi down to Plegia? Nightmare."

"Fair enough," Aversa said. "I think I can arrange that without Validar getting suspicious. So, show up on Carrion Isle and then what?"

"Then we put into play the second stage of my plan."

"Second stage?"

"The first is being worked on by other parties whose names will not be mentioned."

"Emmeryn and Basilio," Aversa said. "Joint defense of Port Ferox, or something more complex?"

"Ahem!" Robin violently coughed. "So, the second stage. We violently bleed these Valm pigs dry as much as we possibly can. I don't care about our losses. All I care about are theirs's. And Carrion Isle is the perfect spot to do it."

"I like this plan."

-Carrion Isle (Three Months Later)-

A black pegasus swooped around the mountain top. Robin stood up near a cleft by the highest point, looking out with a spyglass. Aversa landed beside him, her pegasus tucking in his wings.

"I see them," Robin said, softly.

"More than we expected. Nearly five hundred ships in all," Aversa said. "Maybe a hundred soldiers a ship? Maybe twice that much. They're packed, Robin."

"Fifty thousand, huh?" Robin gave a grim chuckle. "I'm sure the lack of exercise and cramped quarters are getting to them. Well, I suppose we'll give them a little warm-up."

"Would have worked better at night."

"Naturally," Robin said. "But they aren't that dumb."

It was not night. It was an hour past dawn, and hundreds of sails were now appearing over the horizon, carrying the crimson troops of Valm beneath their banner. There were fortifications set up by the only natural harbor on the island's west side, manned by Plegian troops, set to be a killing field against invading troops.

"So they bought the story about this being a good staging ground," Robin said.

It wasn't. Carrion Isle wasn't a desert, true, but it was inhospitable, covered with mountains and hills, crippling logistics, with a dense forest and no clear lines. The defenses Robin had set up involved single-file trails only between outposts. When Valm did take over the island, they'd have to either abandon it, or spend resources converting it to make it viable.

"Robin, if I was attacking, I'd send scout flyers to reconnoiter and flank the island with transports to the north, east, and west," Aversa warned. "If the defenses around don't hold, then the defense might be flanked."

"You just got here. I've been here for three months, setting up my defenses. Flyers will die to snipers and anti-air mages. The north harbor that shows up on their maps is a feint – the opening in the cliffs there don't run into ground, but rocks instead," Robin said. "They might lose a ship or two there. The southern one is a different story, I installed a few fire traps instead, and the brush there burns easily. With luck, the fire will last for half a day, and it will all be impassable."

"And the east?"

"Couldn't get more than a token force," Robin sighed. "Doesn't matter. I've set traps along the path, they won't get to the west in time."

The defense was suicidal. But the advantage to a partially theocratic nation, Robin reflected, is that there was little shortage of volunteers for a suicide mission. But it's not like I wouldn't be suicidal myself given the right circumstances. I'd die for Plegia myself.

"But not today, Robin. We still need you."

"I didn't say anything."

Aversa chuckled, but it was one without humor as the siblings looked onto the island.

"Let us begin," Robin said gravely.

-The Cerulean Ruler-

"Losses?"

"The advance force reports in the hundreds, my lord. The defenses were hastily constructed on this side, but they were ready for us. We've managed to wipe them out, and the bulk of our forces are landing now, moving on to spread across the island."

"Good," the Valmese commander nodded, shifting the blue gloves on his hands. "We sent forces to flank, did we not?"

"Yes."

"And the reports from them?"

"We're still getting them, my lord."

"Unbelievable," the Valmese commander scowled. "I expected a mess, but not something like this. Every inch of those islands took twice our number over defenders, which I expected, but aside from that, everything has gone wrong. The maps suggested that twice our number of ships could land."

"Perhaps the scale was off, my lord."

"And now my reports are being delayed!?" The commander demanded. "The point of flanking was to provide support, but none was received. Send flyers to retrieve them and meet me on deck."

"But the snipers, my lord."

"I gave the orders for no flyers at the beginning, remember? We've taken the defenses, it will be fine."

"Aye, my lord."

The Valmese commander saw him off and slowly strode on deck, making his way to the front. His ship, the Cerulean Ruler, which was in the vanguard of the fleet, was slowly making its way to the island were the soldiers were being staged on shore. It was a lot more densely forested than he'd been told, but he was certain enough that he could use it to supply.

"We'll have to maintain shifts, and prepare for a counterattack by sea," the commander said to himself. "I'd have expected more forces, but perhaps they weren't willing to lose so much. And they've cost us dearly."

"My lord!"

"Ah," the commander turned to see his aide running back to him, panting. "You have the reports? What happened?"

"No word from the east yet, but the north harbor didn't exist. The southern one was barely usable, but it's all in flames now, apparently they trapped up the brush with flammables," the aide reported. "It's gone terrible at both locations."

"No northern harbor? And the …" the commander froze. "Wait. Where did we get the maps from?"

"My lord?"

"Where. Did. We. Get. These. Maps. From?"

"Plegian defectors, my lord."

"You fool!" the Valmese commander roared. "Those were fakes! They were given fake maps in preparation for defection, and this island was rigged to give the impression that there was a defense."

"No one would go to such length-"

"Oh, no. There's one man who would. And it may be too late for us."

"What do you mean, my lord?"

"This is a trap! We were meant to land here in force! Send word to the landed forces, have them make ready for defense!"

"If it's a trap, should we not leave?"

"If I thought we could do it without cost, I'd give the order," the commander said grimly. "But I fear it may be too late. Let him spring the trap, and I'll decide what to do next."

-Carrion Isle-

"Double, double, toil and trouble, fire burn and cauldron bubble," Robin said, softly. "By the pricking of my thumbs, something wicked this way comes."

"Is it time?"

"I think so," Robin adjusted the spyglass he was holding. "It seems… it seems like our forces have all been slain. And they're assembling their defenses."

"Do they know what we're planning?" Aversa asked, alarmed.

"Even if they know it's a trap, it won't do them any good," Robin said. "We cast the ritual, now."

The two siblings stood facing one another and placed their palms against each other. A dark circle appeared beneath them, inlaid with various sigils and runes, and then a second dark circle joined around them.

"By fell blood and fell birth, we call upon our powers," the pair chanted. "The dark forces that slumber beneath the skein of the earth, we demand that you obey our will and come forward. So long as we stand, so long as there is magic, we enact a curse upon these lands. The dead shall not slumber, instead, all those who have fallen shall come back again on this earth, seeking for life to kill, discriminating at nothing. This island shall become a paradise to the crude mockery of human life that they possess."

"I am Robin, Fellblood…"

"I am Aversa, Shadowgifted…"

"…and we command the dark magic pure! RISE!"

It did not come out in a wave, but instead dark magic sigils, similar to the one buried under Ylissotol, scattered all throughout the island, activated. Robin had spent his time turning the island into a giant magical reservoir.

Generations of Plegians had use the island for negotiations, though Plegian negotiations usually meant backstabbing performed by all participants. And this meant corpse. Lots of corpse. Mostly of diplomats, but a good number of highly skilled bodyguard. Plus, of course, the thousands of recently-killed Plegians and Ylisseans throughout the island.

Carrion Ilse lived up to its name.

Robin felt the dark magic and death spread across the island. He watched as they swarmed the Valm army down below, with every dead Valm solider being converted to their ranks. If they stayed behind, the Valm army would be slain outright.

"Even if they don't figure out that the curse doesn't work beyond the island, they're still going to run…" Aversa warned.

"They'll never figure it out. And if we kill their commander, they'll lose command integrity," Robin said. "Targeted strike. Drop me off and I'll take him down."

"Want a hand?"

"It'd be best for you not to get involved. Things could get … messy."

"Ah," Aversa gave a knowing nod. "I'll circle back, then."

-The Cerulean Ruler-

"It's a localized spell field, keyed to bring the dead back to life! Give the order to pull everyone back to the ships and cast off, they aren't intelligent and they won't leave the island."

"My lord, how do you know that?"

"Because I've experience with these exact creatures!" the commander snarled. "This is the work of a specific Plegian dark mage. Go!"

He'd moved up to the front and was fighting off waves off the creatures at one of the docked ships while he watched his orders being distributed throughout the soldiers. If there was one thing Valm, a country with a million soldiers under its command excelled at, it was command structure.

They'd lost almost a thousand men taking the island, perhaps five hundred more to the traps, and now they were going to lose almost five times that amount to the Risen attack. It could have been worse. The trap was probably expected to cost him the whole army.

"Now, for the next move…" the commander looked around as he impaled a Risen clean through the chest. He looked around. "VACATE MY SHIP!"

One of the soldiers near him protested.

"He'll be coming for me," the commander said. "It semes he doesn't learn new tricks. First the Risen attack, and then he'll go for the commander to achieve maximum disruption. But I'll be ready for him. Go, and forward the retreat!"

The men on his ship nodded, and started moving out, running and fighting the Risen as they did so, but fortunately, most of the Risen had been cleared from the deck. Not that it mattered, the commander didn't expect to use the ship he was on to cast off. It'd have to be abandoned. That was one of the other nice things about Valm – they had expendable resources.

On cue, a dark figure dropped out of the sky, landing on the bow of his deck, crashing down.

"If you're here to kill me so that I won't order a retreat, then I'm afraid you're too late on that count," the commander said, coolly. "Your trap was well played, but it ends now."

The figure looked up and started. "Chrom!?" Robin blinked. "Chrom, what on … how did you … what? WHY? WHAT ARE YOU DOING HERE!?"

"For once," Chrom gave a sharp smile and held out a shining silver sword, "I seem to have you at a disadvantage. Hello, Robin. Long time no see."

A/N: You know I realized something – traditionally, when a character gets screwed up, it's a mentor's job to unscrew them. Robin's mentor is a jaded, washed-up time traveler with a cynical streak a mile long and twice as deep and thinks that she'll make anything she touches worse. Chrom had both his dad and Emmeryn, which wasn't too bad (still bad, granted), but now it's … ah … (checks notes). Oh, look at that, presumably it's Excellus and Walhart of all people.

Yeah, this will end great.