Jiraiya hid his surprise. Suddenly things were getting interesting, because what the girl had just said was, The third party I represent will back the Mizukage's claim to power against all future challengers if she can prove herself by making this alliance work and taking down Akatsuki. He was damned if he knew who the third party actually was, though he had a few guesses, but the effect on the others was unmistakable.
Mori Biwako gave her a "We're going to have words about this when we get home, young lady" look, and wouldn't Jiraiya pay to be a fly on that wall. Ryūgamine gave a dry chuckle, which was what he did when he decided that the enemy hadn't brought enough men (which was to say, every damn time). Wakahisa laughed boisterously, with an ambiguous note of approval. And the Mizukage… the Mizukage had a pleasant expression that gave away nothing, because of course she did.
Jiraiya had a distinct sense that he'd just seen a piece of Mist's internal politics that an outsider wasn't meant to see. His mind was already going into overdrive. What did the kid have to gain from pulling this stunt in front of him? How had she even made it to this dinner if she wasn't on the same page as her clan head? How had Mori Biwako, a woman he was pretty sure had already worked out a counter to every one of his publicly known techniques, and at least half of the rest, been taken off guard by one of her own?
The pieces clicked into place one by one. Mori Biwako had the Mizukage's permission to bring her husband to this dinner. That had been a transparent enough show of strength. On even footing, Jiraiya reckoned he could take Ryūgamine three times out of four—but there was no such thing as even footing against a shinobi who never held back, never ran out of firepower and never left anything to chance. Jiraiya should have hated the bastard after everything he'd done, and without a doubt, that woman was watching to see if he'd let his emotions cloud his judgement when suddenly faced with an old foe. But Jiraiya had found, during the war, that by the time you were waist-deep in blood you started to care less which of a thousand enemies had spilled it, and while he might never forgive the man for what he'd done, he wasn't going to spend nights awake thinking about him either.
No, the interesting part was that it was a show of strength against the Mizukage as well. Back in the day, Mori Ryūgamine had been tipped for the hat, and to this day it was unclear (at least to Leaf) why he'd yielded it to the younger and less experienced Yagura. It wasn't the Frozen Skein. That hadn't been in Ryūgamine's Bingo Book entry, suggesting that he'd married into the clan and his logistical brilliance was entirely his own. Bringing him to an event like this was a show of support, a trial for Jiraiya to overcome while the Mizukage watched and waited for opportunities. But at the same time it was a reminder for the Mizukage to toe the party line. She was replaceable, and they didn't want her to forget it.
So the Mizukage had allowed Mori Biwako to bring him here. It was ultimately in her interests, and Jiraiya suspected it would have cost her to refuse. She wanted a controlled environment, without a large audience, but she also didn't want to be forced into siding with Jiraiya if it came to a two-on-one conflict against the Mori, so she invited Wakahisa—she had the necessary pretext, the "family gathering", and presumably she expected him to ally with her if push came to shove. Jiraiya didn't know enough to tell how justified that was, or why.
Now, assuming that enormous chain of guesses and assumptions was right, Mori Biwako had taken advantage of one family member's invitation to bring in another. The kid—no, it was worth making a note of her name now—Mori Ami was an effective counter to that woman's efforts to restore the numbers advantage, and with the former Mizukage candidate and a third faction's representative on board, the Mori clan head must have been preparing a serious blow against the Mizukage. Jiraiya imagined she'd force her to commit to something big in front of him, something which would strengthen the Mori's position and advance their own agenda in the negotiations.
All within the context of a pleasant family dinner, of course, without any of those other pesky diplomats to get in the way.
Then her darling grandsomething had swept the carpet from under her. In a context where the Mizukage was being reminded of her vulnerability before her backers (which Jiraiya assumed the Mori to be), Mori Ami was offering the woman the support she needed, on the condition that she follow Ami's foreign policy. At the same time, she was essentially holding the threat of alliance with the Hokage over everybody's head, saying that if they weren't going to steer the negotiations the way she wanted, she'd back the Hokage who would. Jiraiya almost wanted the Mizukage and Mori Biwako to turn her down just so he could see what her game plan was for supporting the sovereign leader of another state against her own. He doubted she was going to go the Keiko route.
Oh, and technically there was a message in there for him as well. If he didn't put his money where his mouth was when it came to making this alliance, then he would become the common foe, and Ami's faction would make sure Mist unified against him. Without any knowledge of what that faction was (something Ami was blatantly taking advantage of), Jiraiya had no way of evaluating the threat. Not that it mattered. She was either on board with his key diplomatic goals, or pretending well enough to serve his purposes, at least for now.
