"Sure, sure," Tatsuya said, glancing at his siblings with a (fake) fond smile. "I'm sure I was almost as small as you at your age..."
Something they would know to not be true. He had been small as a child, but that was probably before their memories; to them he would always have looked tall anyway. Just a bit of teasing, and all.
It was only fair, when they were being little brats at the moment.
"Yes, let's get going," he said easily. His expression didn't change at the change in address Hoshikata used on Akane, but he wasn't really surprised. He hadn't expected they'd get along well for a while, if ever. "I don't mind walking at all either, I'm certainly probably the most able to here."
He returned Natsu's look with another, less-subtle once-over. Whether it was genuine interest or an attempt to reciprocate the flirtations for some other means, he'd take either one. He was already engaged, but it had never bothered his fiancée that he did this sort of thing, and he didn't mind the twins' comments. Well, except for needling them back, on principle.
"Well, we are on a diplomatic mission," he said carelessly, as if he didn't suspect at all that every single person there had ulterior motives. "Although staying in the tourist area sounds more fun to me, I'll leave that up to my friend here. It is, after all, his mission and not really mine." He gave a sweeping gesture toward Hoshikata, with a wide grin. It appeared most of his facial expressions could be summed up as some type of smile.
And there wasn't really a trace of deception in his face either, which had come from long practice. No, he genuinely looked as if he didn't have a care in the world except flirting and slightly irritating younger siblings.
He glanced at the twins. "Best behaviour, and not too much sugar. You know mother will tell you off for it when we next see her."
Not that he expected that to stop them from eating whatever the hell they wanted, but at least he wouldn't be the one who got in trouble if he could at least say he tried to tell them to eat healthy. He was mostly sure they could take care of themselves there, anyway. They certainly had managed fine without him before.
Would it be a better idea for me or Hoshikata to ride with him? Probably him, for consistency's sake, but it was entirely possible--almost definite--that his friend was playing some sort of odd diplomatic game with Natsu that he shouldn't disrupt. Then again, the flirting might distract the diplomat somewhat, although if he was also a spy like Hoshikata was...well. He didn't think he ran much risk at being found out as fake, as you had to know him quit well indeed to even begin to figure that out usually, but that was also an option.
"Well, I'm the one with the most stamina," he said with a suggestive look. "So I think I ought to be the one to ride with you, our fair host, if that is of course all right with my friend here."
Flirting. The whole. Way. Enjoy, Natsu.