Right after Killian comes back from the dead in "Last Rites," as they walk back to Granny's from the cemetery.
"I can tell that your heart is uneasy. And it's my job — well, I hope it's my job to protect your heart, even when no one is physically trying to steal it." - 4x21
They walked across the graveyard, Emma's hand gripping tightly to Killian's. She hardly ever took her eyes off him, afraid that if she looked away he would disappear in a mirage. She assured herself with the warmth of his touch as she watched the raindrops fall over his face.
They stopped abruptly when Emma spotted the headstone she had visited just a couple hours before. The rum flask still sat at the base of the grave.
Emma whipped around quickly, placing her hand over the heart of the man next to her. She could feel it beating beneath her palm. Her eyes met his and she took a breath. "Swear to me you are actually here, and you're not some desperate hallucination in my head?" She asked quickly. "And I am willing to rip out your heart just to check that it's really there," she added in all seriousness.
"Emma, it's really me. I am alive," he replied earnestly. "And I have every intention of remaining that way."
Emma ran her thumb gently over his cheek and nodded. "Okay," she sighed. She swept up the rum flask sitting at her feet and pressed it against his chest. "Take this."
Killian put his hand over the flask to take it from her, and he grinned, somewhat amused that she had brought it to his grave. "Why thank you, love," he said with an eyebrow raised, before taking a swift slug. Emma closed her eyes and let out another breath. She was still getting used to the fact that she was breathing easily again, because for the past twelve hours every one had felt painful.
They walked a little while longer in silence, the overcast sky turning darker above them. Emma stopped them again when they reached the street. She pulled the chain off from around her neck and handed it to Killian.
"Put this on," she demanded. "Now."
Killian was surprised by the request, as well as the sudden change in tone. "What, you don't want it?" He asked with a puzzled expression.
"When you gave this to me you told me it was the reason you were alive," Emma explained, still holding it out to him urgently. "And you know what happened right after you gave it to me? You died." Her voice cracked on the last word.
"Emma, I didn't die because I didn't have the ring — "
"Just put it on," Emma insisted impatiently. "Please."
Killian took the chain from her, but hesitated to put it on. "Emma I wanted you to have it," he told her. He squinted his eyes at her curiously. "You aren't usually the superstitious type. Why is it so important to you that I wear it?"
"Because you promised!"
She was suddenly crying, the events of the day finally catching up with her. He had died. She had lost him. And now that he was back, she was so relieved, but she was also angry.
"I have lost everyone I have ever been with," she choked on a sob. "You promised me that you were a survivor, that you would live, and I have now lost you so many times over and I cannot lose you again!" She took a breath as a few tears fell down her cheeks.
She stepped towards him and held his face gently in her hands. "Killian," she said softly. "No matter what kind of dangers I face, I need to know that you are going to be there at the end of it all. I need to know that you are going to be okay."
Killian put his hand on her cheek, wiping away a tear with his thumb. "Emma, I died because of the mistakes I made," he told her. "But I am not alive right now because of a ring." He moved her hand from his face and placed the ring in her palm the way he did the first time he gave it to her. He held it there without letting go of her hand. "I'm alive because of you. Because you risked everything to save me."
Emma shook her head. "But I didn't —"
"Yes, you did," Killian insisted. "I am here right now because you kept fighting for me, even after I died. And I kept fighting for you, even after I thought I'd never see you again." He looked down at the ring between their intertwined fingers. "I promise you, Swan," he said, "that as long as you wear this ring, I will survive. Not because of any superstition, but because it means that you are fighting for me. And so long as I know that, I will still be standing at the end of every battle."
He met her eyes, and Emma gave him a watery smile. "Okay," she agreed with a sigh. "But the next time you want to prove to me that you are survivor, can we skip the part where you actually die? 'Cause I'm not going to the underworld for you a second time." She joked.
Killian smiled back. "Aye, love," he answered softly. "That I can do."
He kissed her deeply, and Emma happily wrapped her hand around the back of his neck. Neither of them noticed the way the ring grew warm between their fingers, or the soft magical glow that sealed true love's promise into the ruby jewel.
That's all I've got so far for moments, folks. I may or may not continue. If you are looking for more OUAT from me, please check out my story The Phoenix!