Notes:
Grima was not given a definite gender in the Japanese version, and may very well not have one. I have gone with Robin's gender for the sake of pronouns and for the ease of reading along with the mental image of fem!Robin in your head.

Also, I have used some information from the Future Past DLCs, but since this is obviously not the same universe, some important details are different from all known universes. Blame the butterfly effect.

Vessel

or, The Tragedy of Morgan
(A Tale in Two Acts)

Act I

She answered Morgan's request for an audience in the evening, after she had finished killing the child of Naga and her friends. With Lucina dead, all immediate problems were out of the way, and Grima could focus on the minutia necessary for holding onto her place in the world.

The first being this one.

Bowing her blue-haired head, Morgan entered, flanked by a retinue of Risen. "Master Grima."

"Well? Do you have him?"

"Yes. Alive and well, as you asked."

Morgan gestured for the Risen to bring their captive forth. Bound at the wrists and ankles, stripped of his armor, his silver sweat-soaked hair sticking to his cheek, Inigo was set onto the floor in a kneeling position. Refusing humiliation, he looked Grima in the eye and said hoarsely, "I'll never betray them."

"Oh, you won't have to. Your princess is dead." Then, in the beat of Inigo's stunned silence, she asked Morgan dryly, "Did you leave him ungagged for a reason?"

"I was afraid he might choke, Master. You said to take no chances with his life."

"Fine. A job well done, Morgan. You may leave."

She saw hesitation in Morgan's eyes before she bowed and left.

What, Grima wondered in annoyance, is praise no longer enough? Is she expecting a reward? Human servants were fickle like that—she'd already culled several of her Grimleal whose loyalty was doubtful after they hadn't gotten quite so much land or riches or power as they wanted. Validar, for one. Meanwhile Morgan had been perfect in her loyalty and uniquely useful in her talents. Grima would rather keep her around if she could.

But Morgan was also the last surviving heir to Naga. Therefore her loyalties were a... sensitive matter.

Grima wondered if the Falchion itself—concealed in the folds of her robe—was calling to Morgan, now that its old master was dead.

Someday her threat would eclipse her talents and she would have to kill her. But not yet. Grima sighed and waved her hand about to summon a pair of Risen. "Go find some flowers somewhere and bring them to Morgan," she told them curtly, then warped them away to a distant plain with a flick of the wrist.

Then she looked down at her prisoner.

His blood's presence was not powerful. Robin's blood was such a pure beacon that Grima had felt it in slumber from the center of the world. Inigo's could hardly even be felt halfway across the room, and then only when she searched him for it. Well, that was to be expected, she thought with annoyance. His father—whose blood was also weak, but twice as strong at least—would've suited her better, but Risen were so terrible at taking prisoners. (Another reason to let Morgan live for the time being.) No, it was good fortune to have a male fellblood before her at all. In the worst case, if the children born of her own vessel would not do, they had some time to try him with Aversa, and she felt fairly confident that somewhere among the grandchildren, at least one would be suitable.

Inigo gazed back. His defiant look was beginning to annoy her. She slowly walked up to him as he kept his measured gaze. Then, without warning, she kicked him in the shoulder and sent him toppling over to one side. His head made a satisfying sound against the stone floor and he gave a gasp. "Oh, did that hurt?"

For a moment Inigo's eyes went vague, and Grima had the presence to regret being rough with him. It would be much more difficult to secure a new vessel if he died. At times—given how hard it was to kill them when you wanted to—Grima forgot how delicate these creatures could be.

Fortunately, he was still breathing, and in moments he'd collected himself enough to struggle against his binds, to no effect. Morgan was always so good at knots.

"Do you know why you're here?" Grima said. Inigo ceased his struggling, but gave no response, simply watching her warily. No matter, it was rhetorical. "It's because you humans are pathetic creatures."

Grima held one hand before her, letting her brand face him. As she clenched and unclenched her hand, her leathery skin rippled and her blue veins moved.

"Do you know how long I've had in this vessel?" Inigo's eyes moved from her hand to her face. "Merely ten years! A blink of an eye, and already, it is falling apart." Grima sighed and crossed her hands behind her back, where they would not embarrass her. "But no matter. What you lack in longevity, you make up for in numbers. I learned that long ago,"—a bitter smile crossed her face at the memory of the first war—"but now, all will be to my advantage."

Inigo had gone still. Grima looked upon his face and saw—determination lingering, yes, but growing fear began to make its way into his eyes. And he looked like he was trying not to cry. Much better.

"I see you require no more explanation. Good."

A few weeks later, after the capital had been fully secured, Grima told her generals, "I'm leaving for three days." Morgan nodded earnestly; Aversa less so.

Grima did not feel confident leaving the castle in their hands, but there was a sword that needed hiding. And besides, their captive had already served his purpose, though she kept that a secret to herself. Though the child had barely begun, she knew already—through some intuition born of her fully awakened powers—that it would do as her new vessel.

So let them free the captive. He wouldn't last long in the wild. If they showed their true colors in her absence over this truly trivial matter, it would save her precious time and energy spent determining their loyalty in the future.

As she took off into the air, she pondered instead what her new vessel would be like. This time, it ought to be raised properly in the palace, carefully prepared for its role—unlike Robin, who still surfaced from time to time to fight her. In a way, Grima looked forward to getting a new vessel. This one was powerful but defective. The new one would have thinner blood, but a willing mind would make up the difference and more. This new one—

Ah, yes, it ought to have a name. Grima was bad with human names. Naming it a dragon name seemed ill luck; she was looking for a vessel, not a successor.

Perhaps Morgan would do. To her understanding the humans named each other the same thing from time to time, and it was a name that didn't disagree with Grima. It meant morning. It was still the dawn of her reign.

And Falchion would be buried deep within Origin Peak: an ocean away from the last humans with ships burnt and mounts slaughtered.

Inigo woke to the sound of someone fumbling with keys. His mouth was dry and his entire body was sore, his muscles exhausted and torn and never given enough food to recover. But—beyond the knowledge that their resistance had failed, the world was Grima's, and his body had been among the spoils—his mind was still sharp enough to notice that it did not sound like the person was his door was Grima.

He didn't dare hope that he was being freed. He'd had enough of his hopes crushed recently. Reflexively, he pressed his knees together.

The door opened, and he saw, illuminated by the torchlight in the hall, long white hair framing a dark oval face. It took a few moments for him to recognize her as General Aversa, whom their resistance had briefly fought (and fled from) a little over a year ago.

He wondered what she wanted. In some particularly insensible part of his mind that still didn't believe that his friends were dead and he was a prisoner, Inigo thought to himself that Owain would probably double over with laughter if he told him how many women were coming after him lately.

"Can you walk?" Aversa whispered.

Her secretive tone made him alert at once. But his hope was short-lived, drowned out by pessimistic voices that had lately taken over his thoughts. Was he being freed? ... Or was she just checking to see if he had enough energy and will to make an escape so she could break his legs just in case?

Before he gave any response, she started work at his handcuffs, cycling through each key on the ring until one finally clicked and the cuffs opened. "If you can't, you won't last long anyway," she reasoned out loud. She opened the cuffs at his ankles with the same key, then handed him the sheathed sword from her side. It was only then that Inigo committed to the idea that he was, in fact, being freed.

He only managed to hoarsely say, "Why are you..."

"None of your business," she said curtly. "Now go. Help is waiting for you in the stables."

Inigo tentatively stood up, leaning against the wall and the sword for support. Blood rushed away from his head, but in a moment the faintness passed, and the sword hilt felt familiar in his hand, and—he didn't know what it was exactly, but he laughed and cried at little at the same time.

Aversa gave him a disgusted look and said, "Your dungeon madness is so becoming. If you'll excuse me, I need to go make other preparations."

"I'll be fine," he said as she left. He wasn't sure she cared, but she cared enough to save his life, and that was enough to make him feel deeply grateful. He strapped the sheath around his waist, unsheathed the sword, and gave a few practice swings. The hilt felt rough in his hand, but his aching arms still remembered the movements.

Adrenaline pumped through him as he peered beyond the door into the empty hallway. He was certain there would be guards, but he was not stopped on his way through the hall, or up the stairs, or in the corridor of the palace all the way to the main doors. It was enough to make him suspicious, holding his sword at the ready as he pushed open the door.

But there was nothing beyond but darkness and rain. Inigo looked about for the stables and ran across to them, thinking—even while fearing a Risen ambush—how wonderful the mud felt against his feet.

In the stable, he found a bundle set out on the floor. He unwrapped it and found a clean set of clothes his size alongside a flask of oil and an herb he recognized upon inspection as olivi grass. The basic ingredients necessary for a waterproofing hex. Thoughtful, but he hadn't the time and energy to cast a hex of that intricacy at the moment. He wished Aversa had cast it ahead of time.

Inigo began to change and was thinking about how it was like his parents were pitching in to help him—the herb his mother was named after and the sorcery his father had taught him—when a scrap of paper fell out as he was putting on the shirt.

He picked it up and squinted at the words, making out the neat print by the faint magic light from the gates.

Take my pegasus and go.

He hesitated, but he hadn't the stamina, supplies, or knowledge to go looking for her. Inigo silently thanked Aversa. He saddled the pegasus—which did not protest his direction, despite his gender; he thought it was a surprisingly calm mount for such a fierce woman—and took off into the sky, clinging to the reins.

As he flew, he started to laugh again, and tipped his head back to wet his mouth with the rain. Maybe there was hope after all.

Grima returned to find the palace at Ylisstol in tatters, and Morgan sprawled out next to Risen corpses with burns on her robes and cheek. Paralyzing sadness leaked over from the girl's mother and for a moment she stopped walking. Then she overcame the vessel and walked forth. Grima was just disappointed to lose such an able assistant.

But as she approached the body, Morgan stirred.

"What happened?" Grima said.

"Aversa," she moaned. "She... she betrayed you, Master Grima... Something... revenge for Validar... She fled with the prisoner... I tried to stop her..."

"I see. Let's have you healed, and perhaps you can recall where she's gone."

"Thank you," Morgan murmured as Grima summoned a pair of Risen clerics. "Thank you for thinking of me, mother."