Ichigo is not used to sitting seiza, and his knees ache and he hasn't been able to feel his feet for the last ten minutes. (Tea ceremonies are long.) If he had to get up, he knows he would stumble.
Nothing in the world will ever convince him Kuchiki Byakuya doesn't know that.
Of course the guy's been sitting like that all his life, so he wouldn't have the same problem. Nothing in the whole of the mortal realm, Soul Society, and Hueco Mundo will ever convince him Kuchiki Byakuya hasn't planned that.
Ichigo stays silent and takes a sip of his tea, though the only reason he does is that Rukia was the one who prepared it, right there under his eyes, and there is no way Byakuya would risk his precious little sister getting exposed to poisoned ingredients. (The fact that Byakuya drank first doesn't help at all, because Ichigo bets he'd have the antidote on him.)
"Kurosaki Ichigo," Byakuya says, cool like a death sentence. "I hear you have taken my little sister as one of your concubines."
Yep, nothing in the universe can possibly convince Ichigo this wasn't intended as a death trap. He bets there's already an Ichigo-sized hole dug out and waiting under the camellias. The fun thing is he knew that from the moment they received the invitation, and yet here they are. He must be suicidal.
The proof is that even as Rukia gives a polite, well-bred, fake laugh, he can't help but mutter, "Other way around there."
And then as Byakuya stares, Orihime blushes and says dreamily, "Oh, I want to be the Sultan next time. Layered silk veils! Reds and oranges and yellow too. Like sunshine and lemons and oranges. Kurosaki-kun is bright and sharp and strong like summer sun and citrus; he definitely needs a yellow outfit."
"I do believe we have bolts of silk in storage," says Rukia modestly, and eyes him up and down. "They'll suit pretty nicely."
Ichigo bets Byakuya regrets not having poisoned the tea now. Ichigo sure does. He drinks his cup anyway.
Rukia made it, after all. You never know.