"We can talk about the seal later, when I'm actually able to contribute something," you tell Briar. "In the meantime, would you mind taking a look at Tatsuki?"
Briar looks over at the unconscious girl. "What happened to her?"
"We asked Ambrose about her seal," you say simply. "He answered."
"...why am I not surprised?" the fairy mutters, before flying over to Tatsuki. After a brief observation, Briar pulls her wand and casts a spell that produces a faint bell-like ringing, and Tatsuki's eyes flicker open.
"Huh?" she asks. "What happened? Miss Masaki?"
"Welcome back, Tatsuki," Masaki says, smiling at the girl.
"...did I go somewhere?"
"Only to the floor," Ichigo supplies helpfully. "You fainted-"
"Like hell I did!"
"Language, Tatsuki," Masaki scolds, absently restraining the girl.
"-right after the old man finished saying that one of your folks helped put those chains on you," Ichigo finishes.
Tatsuki blinks, and pales again.
"Hey, now," Masaki says, her hold turning into a hug. "Don't go passing out again, Tatsuki. It sets a bad example for the twins about how a girl should behave in public."
"We're impressable," the dark-haired twin says sagely, from where she and her sister have moved over to the hug the older girl.
Tatsuki chuckles faintly. "Right. No more fainting." She sighs, gently shrugs off all the arms, and gets shakily to her feet. "So, what did I miss while I was out?"
"Mostly storytime and some speculation," you say. "Ichigo gave us a quick recounting about the history of your family shrine, and our working theory is that the creature your ancestors kept around is at the heart of all this."
Tatsuki blinks at you. "The oni?"
You're treated to the rare sight of Lu-sensei doing a double-take. "What's this about an oni?"
After glancing at Tatsuki, gesturing to your master, and receiving a permissory nod, you quickly recount the tale Ichigo told, and Masaki's belief that it explains where Tatsuki's seal came from. Cordelia seems as mystified as you by that claim, but judging from the way Lu-sensei's expression hardens, he gets what the Kurosaki matriarch was hinting at, and agrees with it. You then add Ambrose's theories about what would happen if Tatsuki's seal were removed. The girl frowns at this and looks to the Kurosakis for confirmation, which she receives in the form of wordless nods.
"So what am I supposed to do?" she says, after you've finished speaking. "I don't want this seal on me when I know it's affecting my mind, but I don't want to grow horns, either!"
"I think the best thing to do is to sit down and have a talk with your parents about this, Tatsuki," Masaki says. "I know, one of them was involved with this seal, and they never told you about it - but do you really think they did it to hurt you?"
"...no," Tatsuki admits in a small voice. "But why-?"
"That's one of the things you'll have to ask them."
Tatsuki takes a deep breath. "Would you come with me when I talk to them?"
"Of course, dear."
"On that note," Isshin cuts in, "we should probably get going."
"Before you do," you interrupt in turn, "I believe I owe Miss Arisawa an apology."
Everyone looks at you. "For what, exactly?" Cordelia asks, puzzled.
Well, let's see. You nosed into the Arisawa family's private affairs, got several complete strangers involved, said some things that upset Tatsuki, and coaxed her into a meeting that ended with her passed out on the floor. That seems to cover it... now the question is, how do you apologize for it?