Disclaimer: I am not the owner of Once Upon a Time or Blue Exorcist

(Today, in Storybrooke)

Coming back into town wasn't like returning home. Rin stood in the streets, expecting things to be relatively similar to how they were when he left. However, that was not the case. An odd purple haze seemed to be fading away from sight, leaving Rin wondering what he had missed while he was out of town. Had he really been gone for long? The emptiness of his stomach told him he probably had, but he didn't want to focus on it.

"Something is wrong here. That haze…it almost looked like magic." Neal glanced towards Rin, who nodded in agreement. Moving forward, he walked slowly through town, searching for what could have caused it.

In the streets, he could see various groups gathering and reuniting. People had their memories back, which must have meant the curse was gone. He saw Snow, standing with her husband and Emma. Near them, Rin saw Blue, talking calmly to them about magic and how it was back in town. Joining them, Rin waved and smiled at the fairy. "Hey! So, the curse is gone?"

Turning towards him, Emma placed a hand on her hip and narrowed her eyes. "Yeah…nice to see you've finally decided to come back. Everyone was wondering what the heck happened to you, especially Henry…" She trailed off, looking away. "Long story short, Regina still had some magic left in this world and put Henry under a sleeping curse, trying to get to me. It may have taken a while, but I finally got rid of this curse."

Her gaze slid over behind him, before her eyes widened. "Wait…that can't be. Neal?"

"Hey, Emma." Neal gave her a half-hearted smile. "It's been a while. Either way…Rin, since they remember, did you want to try asking Blue about that spell?"

Nodding, Rin turned towards the Blue Fairy, while Neal walked towards Emma to have a whispered argument about his return. "Hey…so, about that sealing spell…"

"I know. I saw the flames from our church when you left." Blue gave him a sad smile, touching his shoulder gently. "That seal was never strong enough to hold, I knew that. Such power…I still do not know where it comes from, but magic can only do so much to contain it."

"And you can't put it back? I mean…recasting the same seal should fix the problem, right?"

She shook her head, pulling back and folding her hands in front of herself. "Unfortunately, nothing is ever quite so simple. Magic is not the same in this realm, and even if it were, there are no diamonds to mine for fairy dust. I cannot do for you what I did back then…and now that the seal is gone, your powers seem to have exceeded the level at which they could be contained. No one's magic could make them go away, Rin. However, I can offer you some advice. These powers do not make you who you are. They are a part of you, so as long as you learn to accept that, you can control them."

He knew it would be possible, but it still didn't stop his chest from feeling heavy at her words. Rin didn't want this power, not at all. However, as he was trying to think of what to do next, someone came running at him from the side. "Rin!" Red was there, holding him tightly in a hug. "I'm so glad you came back…I worried that you wouldn't." She pulled back, giving him a smile. "Plus, I'm back to being myself again, so I guess that means you don't have to keep freaking out about the curse, right?"

"Yeah…" Rin trailed off, pulling back and looking away. "But that doesn't mean there aren't other problems to deal with. Red…you do realize what drawing this sword did now, right?" She nodded, biting her lip. "I'm a demon, Red. Literally a demon…I'm just like that monster we were trying to hunt down back home."

"So?" She smiled at him, touching his shoulder and pressing her head against his arm. "You accepted me for what I was, so the least I can do is offer you the same. No matter what you are, you are still Rin, okay? Those blue flames of yours won't scare me away anytime soon."

"And they won't keep me away either." Another person stood behind her, with a familiar small smile and mole on his cheek. Frozen, Rin stared at his brother with wide eyes, becoming acutely aware of Shiro standing behind him, observing everything. "I'm sorry Rin, for everything. All of this…it's my fault the seal was broken."

Looking away, Rin refused to meet his eyes. "It was breaking on its own anyway, so don't worry about it."

"Wait what? How could a seal like that just break on its own?" Snow asked, having overheard their conversation from nearby.

"By not being powerful enough to contain his power. As I told you before, it was not a perfect seal, Snow, but it was the best I could manage given the circumstances."

Blue's response was calm, but none of them seemed to know what to say in response. After a moment, Rin shrugged and looked up, giving Yukio a small smile. "Anyway…do you think Gold is going to kill me for keeping this sword? I mean, it technically wasn't his to begin with…and now everyone remembers that too."

"You have two strangers hunting you down, and just ran away after erupting into blue flames, and that's all you're worried about?" Yukio chuckled after a moment, shaking his head. "Same as always, you never worry about the right things. Maybe there is reason to worry about Gold, but I highly doubt you're his top priority. He seemed more interested in tracking down the people who took your sword, not you, Rin."

"And that'll be its own disaster." Shiro finally spoke, moving closer. "He has no idea what it is he is hunting down. I suggest you find a way to keep him out of this. It is a matter for exorcists like myself and Neal to deal with, and you should not get involved."

"Exorcists? Rin…why would you find someone like him? He hunts demons! Do you even realize what that means for you?" Yukio stared at him, his eyes wide.

Nodding, Rin looked away. "We're figuring that out, Yukio. I mean, I kinda didn't have much of a choice when we ran into Satan anyway…they really wouldn't stop following me when I realized he was here too."

"Satan?" Red frowned, staring at him. "Who is that?"

"The demon we kept encountering in the Enchanted Forest." Rin looked over towards her, smiling ever so faintly. "He's kinda the king of all demons, according to Shiro and Neal. We were in way over our heads against that guy, trust me."

"And he is also the demon who sired Rin." Shiro spoke, while Yukio seemed to grow pale, rising to his feet. Even Red blinked in surprise, gazing at the priest with wide eyes. "There is no doubt of it. Only one demon in history has ever possessed the ability of the blue flames. For Rin to have that power as well…he had to have inherited it from his father. Luckily, he still has a hint of humanity in him from his mother…enough that I am wiling to consider an alternative to eliminating his power other than death. If we hurry, we may be able to find a method of containing it before the Vatican hears that he is still alive."

"Wait, are you saying you'll kill him if we don't contain his power?" Snow spoke, stepping forward with narrowed eyes. "I don't know who you are, but that's never the right answer. No one ever has to die…there is always a better way that keeps everyone alive and safe."

"But if I do not kill him, someone else will. That is the very nature of my organization." Shiro sighed, shaking his head. "For now, I suggest you begin thinking of some other method to seal away his flames. If he is seen igniting into flames like that by anyone else…word will reach the Vatican, and they will send back-up for the mission they've given me. No one expects an exorcist to fight against Satan alone…because every team to go against him before has always perished."

But you'll win, Shiro! I know you will, because you're the greatest exorcist to ever live. Kuro's words made Rin smile, bending down and scratching his back.

"You bet he is, Kuro. We'll find a way to stop him…and if not, at least I can give him what he wants so he'll leave these people alone."

"And what does he want?" Yukio spoke calmly, keeping his gaze level with his brother.

Meeting his eyes, Rin took a deep breath. "Me. Satan wants his son…and I'll give it to him."

"If you do that, then I'll—"

"Don't say it." Rin looked at the ground, interrupting before he could reveal that they were brothers. "I know what you'll try to do. It's what you've always tried to do…protect me, no matter the cost to yourself. This time, can't you at least let me try to return the favor?"

"Rin…don't you realize that you've already done that? You fought on my behalf, and you struggled to better yourself so you could train me when I was forced to become a part of Regina's army."

"Plus, he's not the only one who'd try to stop you." Red smiled, patting his shoulder. "I can think of one wolf who'd track you down no matter where you ended up at. So, don't expect us to just let you leave so easily."

And don't expect me to let you keep my son away! A different voice filled Rin's head, making him snap up to his feet and pull away from everyone. His eyes went wide, searching for the blue flames but not finding them anywhere. Hello, my son. I never got the chance to properly speak to you before. Now, why don't you just sit back and let me have some fun while we chat? It's been so long since I've had a body that lets me truly enjoy this world, after all…and yours is just perfect for the task.

Shaking his head, Rin tried to drown out the voice by covering his ears with his hands. "Shut up! Get the hell away from me."

Well, it seems that rebellious stage has still not faded away. Such a shameful way to speak to your father. I'll teach you—

"You're not my father! There's no way in hell that a father would treat his own kid like this." His body shook, this time feeling heat crawling under his skin. Satan was inside of him, trying to take control.

But I am, and I can show you just why I am better for you than all of those pitiful humans you call friends. Do you think they care for you? Just take a look at what they did to you, my son. They saw danger, and tried to make you like them. They took away that which made you different, which made you special and connected to your true family. Is that what a friend would do? Or is it the actions of a deceitful enemy? I assure you, I've never once attempted to steal your power away, my son. No, all I've ever wished to do was find you…the one person from both worlds that could show humans that coexistence is possible…that could show them that everyone in both realms should bow before my power.

"That's not coexistence!" He was breathing hard, trying to fight back. However, he could see flames flickering in and out of existence on his arms.

When Satan spoke next, he managed to take some of Rin's voice with it, speaking out loud as well as in Rin's mind. "Then what is, my son? Tell me, how would you define a peaceful coexistence between our kinds? For they have killed thousands of us, just as we have killed them. I am the only ruler the demons will ever respect! Therefore, it is only fitting that I rule over both worlds in unison, the greatest power to ever exist for them to all bow before!"

"Never!" The layered tone in his voice vanished as Rin tried to take control back. Everyone was watching him, their eyes wide as they backed away. Shiro looked grave, one hand looking ready to throw a grenade of some kind at him while the other arm held people back. "Coexistence is about accepting people for what they are. Let humans rule over themselves…stop trying to kill them…and try to become their friend. By being friends with them, you can show them that you can change…that there might be peaceful demons out there, like Kuro, who don't want to hurt others."

Be their friend? Me? Ha, don't make me laugh. Exorcists never accepted me…they killed my beloved Yuri, forcing her to strain herself too much in her flight from them. If you don't believe me…I can show you exactly what they did to your human mother, the reason why they are so much more monstrous than I could ever be.

"And I don't care! That's in the past, and it can't be changed. Looking towards the future, we have to let crap like that go, or we'll never stop fighting." Standing up, Rin was finding it easier to keep Satan at bay. "Go back to Gehenna where you belong, Father. Maybe I am your son…but I'm also Yuri's son, and that means I can choose to live in this world instead of yours. I choose to be like her…to fight for this peace in my own way, without you trying to ruin everything with your anger and hate."

Anger? Hate? Such emotions are natural for demons. Maybe one day you'll see…and when you do, I'll be waiting for you, my son. I'll be waiting for you to join me when your ideals fail you and the humans betray you. Until then, I will give you a chance to prove your methods. Fight for coexistence your way, but I will return the moment I see that you've failed…and then I will rule over both Assiah and Gehenna as one.

The presence faded away, leaving Rin feeling weak. He collapsed on the ground, his legs giving out as he sagged forward. Shiro caught him, guiding him down to the ground with concerned eyes. "My god…this boy…he just held off Satan himself." Shiro chuckled, shaking his head.

"Indeed he did. He'd make a fine exorcist, don't you agree?" Mephisto spoke, appearing by his side with a smile on his face. On his shoulder, a green hamster seemed to rest with an irritated expression. "I sincerely hoped he was capable…otherwise, I suppose I would have made Father quite angry with this plan of mine. Do you think his dreams is possible, Shiro? That one day…us demons could live here in Assiah peacefully?"

Looking down towards Rin, Shiro smiled faintly. "Maybe one day…if anyone is capable of it, I imagine it would be the son of the one who first dreamed to be friends with your kind."

"Indeed it would be. I wager he'll become the best exorcist in history." With a smile, Mephisto bent down and picked Rin up, who was too weak to object. "Don't worry, I'm taking him to the Academy, not father. After all, it is the best place for him after this mess."

"Wait, what? I'm not letting you just take him away!" Yukio moved forward, while Red stood by his side and nodded in agreement.

"Then join us! True Cross Academy, a school for exorcists, will welcome you with open arms. I can even get around that pesky lingering curse at the town line for you so you can leave for Japan. What do you say? Do you want to become exorcists?" Mephisto smiled, leaning close to Yukio. "After all, it would be interesting to have both sons of Satan under my wing."

"Both?" Shiro blinked in surprise, while Yukio offered a weak smile.

"Yes, both. Rin is my twin brother." He sighed, nodding towards Mephisto. "And if you are taking Rin, then I will gladly accept your offer and join you. I will not abandon him like I did before…"

"Excellent! Then let us be off." Mephisto spun around, dragging Rin away. Shiro and Neal followed shortly after, but Rin was still lost in thought. He was going to be training to be an exorcist, just like the priests that had always taken care of him. It made him smile, because in a weird way, he'd be protecting others just like he always wanted to do. Maybe Satan would come back one day, and maybe he was a demon. Either way, he had a future to look forward to, one which just might lead him towards a future where he'd be accepted by others no matter what he was.

So, here's the end. I know, it was rather anti-climactic, but I was running out of ideas with this one and this was how it ended up, almost like an altered origin for Rin and Yukio who are now going to start training as exorcists. Still, I loved quite a few moments in this story and hope you did as well. Thank you all for reading, and please leave a review with your thoughts on how it turned out!