After her revelation, Itachi ended up fully trusting her. It was strange and fun, and it made her extremely happy. One night, when Kisame stayed sleeping outsid, which he could afford given the heat, Itachi approached her while she was talking with Sasuke. Naruto had already been at Mount Myoboku for nearly four weeks, so he wasn't there to witness it.
"Now I understand why you feel like Seina is also your older sister," Itachi said to Sasuke with a faint smile. "It's because she is your sister, and much older, isn't that right?"
Sasuke choked. He looked at her. Seina, who had forgotten to tell him, burst out laughing as she showed why Itachi knew. Contrary to what she might have expected, Sasuke simply sighed in relief.
"It's great having someone else in the loop. That way I don't have to watch my words so much," then he looked at her again and spoke mentally. "Does he know about… you know?"
"No. I kind of want him to find out himself, just to see his reaction."
Sasuke let out a quiet laugh.
"It's rude to speak in front of someone else, you both know that, right?"
"Sorry."
"So, do you also think of Seina as your older sister?" Sasuke asked Itachi.
"Hmm... not older. Maybe the same age, metaphorically speaking."
Seina couldn't hold back a huge smile when she realized that Itachi was acknowledging that he felt like she was his sister. She leaned over her seat to give him a kiss on the cheek under Sasuke's amused gaze. Itachi accepted it without pulling away, without blushing, and without showing the slightest resistance.
"Now it's like you've given her permission. Just wait until she starts giving you hugs, cheek kisses, and 'loving' punches."
"Hey! The only one I hit a little hard was the old pervert."
"A little?" Sasuke shuddered. "You broke his ribs."
"He was staring at my chest so hard he figured out my real bra size!"
Sasuke and Itachi both frowned, a hint of anger in their expressions as they remembered why she'd hit him. In that moment, they looked so much alike that Seina had to suppress a smile — they looked adorable standing there together. She missed Naruto then, seeing Sasuke with Itachi like that, as if they'd always been close.
"Maybe he needs another Tsukuyomi as punishment," Itachi said, as if discussing the weather. Sasuke snorted with laughter but didn't seem alarmed by the idea.
"That might be too much. If he does it again, I'll break something else. Don't worry."
She winked at them mischievously, stifling a laugh when Itachi froze and Sasuke cringed, curling in on himself to protect his groin as if she was about to hit him.
"What do you think your father would say, if he were alive, if he found out someone was spying on you?" Sasuke asked, amused.
"When he tested our seduction skills, he said my father would kill him. So, who knows."
"Seduction skills?" Itachi asked. "What do you mean?"
Sasuke explained what they had done a few times: targeting people, seducing them, and extracting information. It would've been an understatement to say Itachi wasn't entirely convinced that Jiraiya had been the best teacher for that kind of training. To be honest, she didn't think so either but at least they had learned something. Especially Naruto. When they explained what had happened to her brother the first time, Itachi couldn't help but let out a soft laugh and an amused smile.
"Did you ever do missions like that?"
"Yes. I didn't like them much, but I did them," Itachi sighed. "Some people are lucky never to get those kinds of missions."
She sensed what Sasuke was thinking before he even said it. She gave him a light smack on the head that he didn't dodge.
"What!? It's true! They would never have given the dobe a seduction mission. He's less subtle than a bull in a china shop."
Itachi snorted again, while Seina smiled.
Naruto returned with Jiraiya the next day, on June 1st. He was smiling, tan, and full of energy. Seina didn't know how he did it. Sometimes she got tired just being near him.
"NEE-CHAN!" he shouted at the top of his lungs, picking her up as if they hadn't seen each other in months instead of weeks. "I can't believe it's been so long since I saw you!"
"What are the rest of us, dobe? Chopped liver?"
"You're unbearable, teme!"
"Ugh," groaned Jiraiya and Seina in unison, while Kisame grinned like a madman and Itachi rolled his eyes.
Seina patted her brother on the shoulder but he wouldn't stop hugging her like a tick. She noticed that part of him felt... displaced. Maybe because he sensed her growing closeness with Itachi? She promised herself to spend more time with her brother, hugging him tightly.
She listened as Naruto explained in great detail everything he had learned. Apparently, he had mastered partial transformation at will and could now use senjutsu with his clones, eliminating the need to rely on the toads. Jiraiya had modified his seal, placing a more restrictive one, to give him more control over his Kurama-yang. Her Kurama-yin inside her grumbled insults when he realized Naruto was further imprisoning his counterpart due to lack of control. Seina still didn't quite understand what all of that meant.
When she entered Naruto's mind to see what his Kurama was saying, she saw the bijuu completely immobilized by several torii or Japanese gates on each limb. Her heart sank at the sight. Naruto's Kurama-yang, fully awake, looked maliciously at his brother when she appeared.
"Why did the pervert change your seal?" she asked, trying to contain her anger.
"He said that with this new seal, I could access Kurama's chakra more easily without having to fully open it like you do. That I didn't have time to negotiate with Kurama and learn chakra control like you have with the Eight Trigrams Seal before our time outside the village ran out."
"Did you know it would turn out like this?" she asked, disgusted. "Did the pervert explain that part to you?"
"He just told me that."
"And you're okay with this?" she asked again, pointing at the other half of Kurama, pinned to the ground like a slave.
"...No, but what can I do?"
"What do you mean what can you do? Since when do you back down from training just because it's hard? And since when do you think it's humane to dominate a living being like this, Naruto?"
She was so furious she abruptly cut the connection. Her hands were trembling, fuelled by the rage of her Kurama, who was too angry to even speak. As soon as she left Naruto's mind, she sought out Jiraiya's eyes. She barely held back the urge to punch him in the face with all her strength. The words she managed to force out came out trembling with anger.
"You. I want to speak with you. Alone."
"For what?"
"Are you deaf or what?" she raised her voice slightly, unable to help it from her irritation.
The others were sitting around them, watching in silence. Sasuke frowned when he realized he couldn't sense Naruto through her anymore as she had shut off their connection. Naruto looked angry, sad, guilty, and devastated when he realized she was right and was punishing him through their bond. Kisame and Itachi, meanwhile, were staring at Jiraiya with malice and a calculating look, respectively. She stood up, waiting for Jiraiya to do the same.
Kurama roared in her head when he saw Jiraiya wasn't lifting a finger. The three of them knew exactly what she wanted to talk about, and Jiraiya wasn't even taking them seriously. Seina acted almost without thinking. Nine adamantine chains shot out from her stomach, glowing with Kurama's demonic chakra, and caught Jiraiya before he could jump and evade them. She silenced the pervert before he could open his mouth and vanished with him without even having to consciously shape her magic.
They reappeared on the other side of the island, far from Sasuke and Naruto so they couldn't intervene. Jiraiya looked at her somewhere between fearful and defiant, but the moment Kurama emerged from her seal, as tall as a three-story building, he quickly tipped toward terrified. She restored his voice, but kept him bound so he couldn't use his chakra or escape.
"How could you even think of doing what you did?" she hissed, having lost all the respect she'd once had for Jiraiya in an instant. "Is this how you treat Kurama after everything? HOW THE HELL is my brother supposed to cooperate with his other half when IT'S CHAINED UP LIKE A FUCKING SLAVE?!"
Her shout echoed across the beach as her fury overwhelmed her.
"Naruto was never going to be able to use Kurama's chakra with his previous seal! Maybe in a few years, but he doesn't have that time!"
"And now you think Kurama is going to work with him?! At the first chance he'll try to screw my brother over because you're too much of an idiot to hold the line! Naruto could have learned to control Kurama's chakra in the time that's left, but you didn't even try!"
"You haven't been the one attacked twice by your brother in transformed state! Maybe you're too blind and too close to the Kyuubi to see it, but Naruto doesn't have the kind of relationship with him that you do!"
"And now he won't, no matter how hard he tries! It'll take months or years to regain Kurama's trust! DON'T YOU UNDERSTAND?!" she screamed at the top of her lungs, completely enraged.
"You, human, have proven once again why the bijuu do not trust your kind," Kurama hissed for the first time, lowering himself until his snout was just inches from Jiraiya's pale face. "The Fourth Hokage used the other seal because it was more merciful. He trusted that his children would be able to use my chakra without subjugating me like you just did. And you've pissed all over his legacy without a second thought. Congratulations."
"I don't even want to look at you, Jiraiya. I mean it. I don't know how to face you without punching you and cracking your head open like a fucking coconut. How dare you do something like this without explaining everything to Naruto first?! Why didn't you wait to talk to me so I could tell you what an idiot you can be sometimes?!"
Seina shook her head, pacing back and forth to avoid looking at him and to burn off her rage in the sand. Kurama withdrew back inside her, forcing himself not to incinerate Jiraiya with his chakra. She removed the chains, taking some grim satisfaction in the burns they had left on him, and vanished again. She didn't want to cast a torture curse on him, no matter how much she wanted to vent right now.
She reappeared on another stretch of the deserted beach. No one was there, as expected, so she sat in the sand and stared at the ocean. She was, they were, so angry that she couldn't think clearly. Jiraiya had made a terrible mistake, and it had to be fixed, because she wasn't about to allow Kurama-yang to spend the rest of his existence imprisoned inside Naruto, or forced to agree begrudgingly not to harm her brother in exchange for release.
She noticed Sasuke hovering at the edge of her mind, though he didn't intrude once he sensed how furious she was. She didn't even try to listen in on Sasuke's predictable interrogation of Naruto or anyone else's. Right now she didn't want to talk to anyone. She waded into the water, summoned one of the white sharks she'd been training with for weeks, and let it take her away somewhere to clear her head for a while.
A few hours later, when she was tired of exploring the ocean floor, and of screaming into the depths to release her anger, she surfaced again.
"Thank you for staying with me, Samjiro."
"You're welcome, Seina-sama."
The shark vanished, leaving a small whirlpool in the waves, and she emerged from the water completely soaked. With a flick of her hand, she dried herself. Waiting for her on the beach, unexpectedly, was Kisame. He was sitting casually on the sand, clearly knowing where she'd gone, but neither in a hurry nor concerned.
"You're finally back."
"Hn."
"Great. Now you're answering me like Itachi does."
"I'm too angry."
"Yeah, we noticed," he said with sarcastic humour. "Sasuke got the whole story out of your idiot brother. Itachi and he aren't very happy with what the old man did. I figured it was only a matter of time before he screwed up."
Seina raised an eyebrow at her teacher. Kisame, somewhere between amused and serious, glanced at her sideways.
"Haven't you noticed? The old man is clearly more attached to Naruto than to you. Probably because he shares more in common with him than with you. They're both a couple of blockheads, and you outclass them both by miles. It's easy for him to feel intimidated by you now that he doesn't really have anything left to offer you."
"And what does that have to do with what happened?" she asked wearily.
"Simple. He wants Naruto to catch up to you because, in some way, he identifies with your brother and feels like he's falling behind compared to you. And it's true. But he shouldn't be comparing you two. That's his mistake."
"You think... he modified the seal to make faster progress at Kurama's expense, just so Naruto could use his chakra like I do and catch up with me in training?"
"That's the impression I get. I told you, he's a fucking idiot."
Seina laughed bitterly, though she thanked Kisame, sensing he was probably right. Hadn't Naruto said countless times that he wanted to catch up to her? Why would training be any different? Jiraiya and Naruto had fed off each other in the worst way. Being away from everyone else hadn't helped either. No one had been there to tell them they were acting like idiots.
"I shouldn't have left Naruto alone with the pervert for a whole month," she groaned irritably at herself.
"What's done is done. The real question is: what are you going to do now to fix this mess?"
"I'm going to modify that damned seal," she promised.
"And what about your brother?"
"I don't know. Right now I'm too angry to think straight. I want to punish him, and Jiraiya too, but I don't know how, because if I do it right this moment, they'll both end up with broken bones."
"I saw the burns. What's a few broken bones?"
"No. Broken bones heal too easily," she shook her head. "I want something that will weigh on them for a while. Especially on Jiraiya. It's clear Naruto had no idea what that new seal really meant."
"I knew there was a reason I liked you so much," Kisame grinned toothily.
Seina immediately sensed Sasuke and Itachi nearby. She saw them waiting in the treeline by the beach. The moment she nodded, Sasuke appeared at her side in a swirl of leaves.
"I see the dobe's really screwed up this time."
"I'm not in the mood to talk about it again. Where's Naruto?"
"In his room."
"Jiraiya-sama is somewhere else on the island, far from the tent," Itachi reported.
"Not surprising. My tent's barriers probably reacted to him because I'm so angry."
"Meaning, he won't be able to enter it?"
"Exactly. Naruto has another tent. I gave it to him so he wouldn't have to sleep outside."
The following days passed with Jiraiya avoiding her and Naruto walking on eggshells every time they crossed paths. Her brother looked sad every time he saw her, but she was too angry to care. At least not until she modified that damn seal. Kisame and Itachi understood what she was up to, so they gave her the afternoons off so she could study the new seal and plan what to do with it. Sasuke, on the other hand, seemed to be punishing Naruto in the way she couldn't. First by yelling at him, then by smacking him so hard even she felt it, and finally by taking Jiraiya's belongings from his room and handing them to Naruto so he could return them to him.
Even so, she didn't forget, nor let Sasuke forget, Itachi's birthday. She crafted one of her bottomless backpacks so he could carry everything he had accumulated over the years and hidden in safe houses throughout the Land of Fire and in scrolls. Sasuke, since he couldn't buy anything in Uzushiogakure, asked for her help preparing an enchanted new wardrobe for his brother. Kisame, who wasn't used to celebrating birthdays, asked her to send him to the Land of Fire so he could buy a box of dango for Itachi as soon as he saw what they were preparing in their free time.
On June 9th, they all celebrated his freshly turned 22 years, much to his pleasant surprise.
"Did you think we were going to forget?" Sasuke asked him with a pleased smile.
"I guess not. Thank you very much for the gifts."
She sensed Naruto before she could even see him. He appeared from behind a tree with a contrite expression, a wrapped gift in his hands. The four of them stared at him. Kisame with indifference, Itachi with a neutral face, Sasuke with irritation and exasperation, and she... didn't know what to feel. In the end, Itachi glanced sideways at her, and since she didn't say anything to tell him to leave or to stay, he nodded at Naruto. He sat down between Kisame and Sasuke, handing a package to Itachi along with his congratulations. They watched as Itachi opened the package, which contained a collapsible shoji board with hand-carved pieces, surely made by Naruto.
"Well, I'm leaving before someone starts crying," Kisame said brusquely, getting up and walking away as if nothing had happened.
As soon as he disappeared, Naruto spoke.
"Can I talk to you for a moment?" he asked her.
"Talk."
Naruto sighed when he saw she had no intention of getting up and walking off with him to talk alone. Itachi and Sasuke, sitting beside her, didn't say a word to mediate between them.
"I've been thinking about what Sasuke said, and he's right," Naruto sighed again, as if admitting that Sasuke was right was harder than admitting that he himself was wrong. Ironic. "I screwed up. I should've asked what the seal was about or, when I saw it, refused to use or modify it... but I was sick of training with Kurama being an uphill battle, you know? You basically mastered the training on your first try, and I almost killed the pervert a couple of times, though luckily nothing serious happened."
"Maybe you should stop comparing yourself to me," she recommended, still angry. "Not to mention how you're dismissing all my effort like it was nothing. On the first try, Naruto? I've been interacting with Kurama-yin since before I was even ten, while you haven't put in that effort. Sure, maybe I was able to master his chakra right away once we started training, but do you think getting along with him had nothing to do with it?"
"I know..." he said, head bowed. "I thought it would just be about using his chakra, that he wouldn't mind giving it to me, like Kurama-yin does with you, and that I would just have to practice with it, but... I didn't realize the most important part wasn't controlling his chakra but cooperating with him. He's almost always silent, observing, ignoring me, and I thought that's how he wanted to interact with me. Now I've realized he probably acts that way because I haven't made the slightest effort to connect with him, unlike you, and my half knows that and sees how different we are."
"I hope you know that I'm going to modify that seal, if you want to fix this. Otherwise... I don't know if I'll be able to look you in the eye."
Naruto nodded without raising his head. Little by little, Seina's anger faded, leaving her exhausted.
"Do you know why I hate that seal so much?"
"Because it has him bound."
"Because Seina's own blood family locked her in a cupboard under the stairs," Itachi said suddenly.
Naruto raised his head involuntarily to look at Itachi as he processed his words. Then, as if he'd been slapped, he went pale as milk when he finally understood why she felt the way she did. Seina was part of Kurama's new family now, just as her relatives had been for her. And Naruto was her brother. Naruto had enslaved Kurama, just as her so-called family had enslaved her. Seina, more than anyone, knew what it was like to live locked away and subjected to the will of someone who hated her but didn't mind using her as a slave because it was convenient. Now Naruto had become Petunia, someone who was supposed to love her because they were family but did exactly the opposite.
Kurama hissed as he saw her memories. Seina could feel again his frustrated malicious thoughts from when he had once considered slowly killing the Dursleys. Meanwhile, Naruto looked on the verge of tears as he realized what he now represented to her.
"When can you modify the seal?" he finally asked, keeping the tears at bay through sheer will.
"Tomorrow."
"Great. Seina, Kurama... I'm truly sorry."
She sighed, seeing that Naruto truly meant it and that he finally understood the full extent of his mistake.
"Come here, idiot."
Naruto threw himself at her the moment he heard the implicit forgiveness in her words. They hugged for a long time. Her brother held her tightly, as if afraid to let go or that she would disappear, and cried silently on her shoulder while whispering again and again that he was sorry.
"It's okay, Naru. I forgive you."