The plot's about to get a bit more complicated (Chromplicated). If something really doesn't make sense, ask and I'll explain. If it's confusing enough, I'll go back and change it.
Once the army was safe, Robin slipped away. He wanted to be alone. He didn't trust himself. His feet had taken him outside to the familiar courtyard. He looked down at his hands. "What I did…it's…unforgiveable." He was married to Chrom, the ruler of Ylisse and he'd been so easily controlled by Validar. These hands had stolen the Fire Emblem and handed it over to the very man that wanted to use it for evil. How could he trust himself after that? Around Chrom? Around their children?
"Enough of that."
Robin jumped twisting around clutching at his chest. "Chrom?"
His husband had somehow approached without his notice. "Save your energy for helping us track that dastard down."
The tactician waited for his heart to calm down before speaking. "You must leave me behind. He could use me again." He hung his head. "I can't be trusted! This cursed blood in me must somehow give my father." He shuttered at the word. It made him want to vomit. "Dominion over me."
"But he never had full control. You can fight it, Robin, and if he expects you to blindly obey, that might be the surprise we need."
"You, you put too much faith in me."
Chrom grabbed him by the biceps. "I have unwavering faith in you. I have enough faith in you for the both of us."
"You're not listening!"
"I am. You're speaking nonsense." He pulled Robin into a hug. "The deed is done. But you can still try to undo the damage. It's not too late!
Hesitantly, Robin returned the embrace. "All right. I'll…I'll try." He buried his face in his husband's shoulder. "I'm so sorry, Chrom."
"I don't blame you. None of us could have known."
"It's my job to know. What good am I if I?"
Chrom's hold tightened painfully. "You're more than just a tactician. Don't you understand? Your purpose goes far beyond that. We're two halves of the same whole."
"The sword at your side and the wind at your back." Robin whispered into his shoulder.
"Always."
The two husbands simply held one another finding strength.
Reluctantly, Chrom released the other man. "I'm going back inside before it gets dark." He offered his hand. "You coming?"
Robin wanted to take that familiar hand, but he shook his head. "Not yet. I'll stay here just a little longer. You go on ahead."
He hesitated.
"Go, before Frederick rounds up a search party."
"He'd do it to." Chrom gave his husband a soft kiss. "Don't stay too long."
"I won't. I promise." Robin watched Chrom walk back towards the castle. He turned back to the sun letting the final rays warm him. Despite what Chrom said, he was still worried. He absentmindedly rubbed his wedding ring with his thumb.
Lucina waited for her father to leave before stepping from the shadows. After what she just heard, she knew what she had to do. She took a deep breath marching forward.
"Beg pardon, Mother. Might I have a word?
Robin twisted to see his daughter approach. "Of course. What is it?"
"It's about Father, my timeline father." She kept walking until she was in front of Robin. "I have memories of him, you know. From when I was little. Before he…died. He was courageous, and kind, and everyone spoke fondly of him. People say he was brave right up until the very end. I always yearned to know him better and now that I do, or as close as possible, I can see that the world will be robbed of a very great man."
Robin felt himself smiled. "I understand. You love him. As do I."
"Mother." Lucina unsheathed Falchion. "Please, forgive me."
"Lucina?!" He took a step towards her, but Lucina raised her sword causing him to move back.
"Stay where you are, Mother! I have no choice. I must kill you."
"What?! What madness is this?!" Robin had thought they'd moved past all this. He'd thought the four of them were finally a family.
"In my timeline, you…my mother kills my father."
"So you think…" His stomach dropped. His heart seemed to stop mid-beat. "No! That's insane! Why would I kill Chrom? I love him."
"I was not certain myself, until now. I knew he had been killed by his closest friend. Betrayed by someone he trusted."
"Lucina, do you realize what you're saying? You're accusing your biological mother of killing your father. Do you honestly believe she would do that? That I would do that?"
"Having witnessed your bond with him, I doubted it could be so, but today's events make it clear. You are at Validar's mercy which means my mother was as well." Robin winced. "I suspect it's he who forced her to eventually take Father's life. This timeline is so similar to the one I hail from. So, so similar."
"Lucina, wait." He held up his hands. The sword point was inches away from his face.
"My parents never came home. They left to stop Validar and all that returned was Falchion. I was ten. Morgan, poor Morgan, was only seven. If Father is right, then we can change our fates. The time table has been hastened, but if this dark future is to be averted, sacrifices must be made. I am sorry, Robin!"
Hearing his name come from her lips stung more than any sword wound. "You don't have to do this."
"Don't make it harder!" Lucina shouted startling some birds into flight. "It…will be swift and painless. If you have any love for Father, then let this be done."
Robin stared at her. If he truly wanted to, he could easily stop her. He may not have a sword, and he doubted his skill was on par with hers, but he had the Thunder tome he always carried tucked in his coat. It would be no trouble to ignite the area around her and make his escape, even kill her, if he so chose.
But he'd never do that.
Never.
"My life is yours. It always has been."
"D-don't say that, M…Robin!" Falchion shook slightly. "Don't!" Lucina tightened her grip. "That only…makes it harder."
"I would give my life for Chrom, for Morgan, and for you." He chuckled softly at the memory of the ugly coat and 'nightmarish' cockroach. How he practically coached Chrom through his proposal and that awful 'wyvern in heat' line and how could he ever forget 'Chromgradulations'.
"Mother, please."
"I know you will be quick about it." Robin smiled warmly at her. "I love you, Lucina."
"M, Mother."
"I'm ready. Do what you must. I have no regrets."
Lucina's grip on Falchion fluctuated from tight to lose in rhythm with her heart. Male or female, this was her mother. He'd welcomed her with open arms even after she tried to create distance between them. 'I love you just the same as I love that child back at the castle'. He'd said.
If she did this, baby Lucina would grow up without Robin and definitely no Morgan. Could she really do that to her baby self?
"Damn me!" Lucina lowered her sword. "I can't do it! I love you too much!" Falchion slipped from her fingers and fell to the soft grass. "I'm sorry, Mother. I'm so sorry!" Tears escaped from her eyes. "P-please forgive me!"
"My poor girl." Robin took her in his arms. "There's nothing to forgive."
Chrom had seen Lucina in the shadows, the girl was no thief, and doubled back. The way she'd walked had bothered him and now he was glad he had. He gave them a moment before making his presence known. "Are you done, Lucina?"
The young woman jerked back out of Robin's grasp. "Father! I, I can explain!"
He held up a hand to silence her. "No need. You're not the only one who can eavesdrop. I heard every word."
"It's like a family trait." The tactician muttered under his breath.
"Lucina, I know your heart is in the right place, but I trust Robin." Chrom took his husband's hand and though he spoke to his daughter, his eyes remained on Robin. "You cannot shake my faith in him. Robin and I have held fast through good times and ill. We swore to be two halves of a greater whole. You underestimate the strength of those ties, the bonds we share." Now he looked to her. "I believe in them more than some foretold 'destiny'."
Lucina retrieved her Falchion and sheathed it. "That is easier to say when you haven't seen it yourself."
"Luciiiiinaaaa!" Morgan cried racing towards them. He enveloped his sister in a back-cracking hug. "I saw from a window! Why were you pointing your sword at Mother?"
She didn't have an answer. Robin did. "It's all right, Morgan. Just a minor misunderstanding. No harm done."
The youngest released Lucina and clung to his mother's arm. Severa always said he and Brady were the world's biggest mama's boys.
"Lucina." Chrom said recapturing her attention. "Aren't your ties stronger here now than they were in your future? You said so yourself. In this flow of time we are bond tighter than ever, you and I. Not just as father and daughter, but as friends. We can change things. We already have and we will again."
She hesitated before nodding. "Very well, Father." She turned to Robin. "Mother, I hope someday you will find it in your heart to forgive me."
"All ready done." He assured her.
"And I pray…that is, I trust the both of you." She looked from one parent to the other. "Will prove me wrong. That the future will crack and fall apart before our family bond ever does."
"Our family bond will never crack." Morgan declared. "Our bonds give us strength!"