As Mizukage and Hokage, their interaction had always been ... special. The Daimyos and the other Kages seemed to assume that, being two women, they would naturally agree on everything.
Terumii Mei might have been more progressive than her predecessor, but that didn't mean much, coming from a Mist Nin. It amused Tsunade that the younger of the two might also be the one most entrenched in her village's traditions, even as she professed to wanting change. Then again, the Mizukage ought to represent the views of her village and not only her own.
As long as Tsunade was Godaime Hokage, that was their relationship -- cool sympathy born of shared irritation over the idiot men who still thought they had managed to get where they were and stay there without a greater amount of ruthlessness than they, manly he-men that they were, and sharp awareness of, and respect for, that same ruthlessness in each other. They were both kunoichi, after all; being underestimated might be one of the cards they'd been dealt but it didn't mean they had to commit the same mistake as their male peers.
Not that they interacted often, and most definitely never in private.
It changed when Tsunade designated Naruto as her successor, because after the first year he needed some space, for people to get used to going to him and not to her. Also so that he'd stop shoving his paperwork at her, damn it.
Mist was the village the other allied countries had the most bad blood with. Obviously it was the one that would do best with a semi-permanent ambassador.
Hosting a previous Kage as such was both a threat, and a mark of deep respect. The Mizukage was a fine appreciator of both.
Their friendship was a strange thing -- not only because both knew that behind the shared understanding and feminine solidarity there was a knife waiting, just in case, even while they laughed. They looked the same age, but Tsunade was over twenty years older than Mei. She could have been her mother, except that Tsunade had never been anyone's mother. After Dan had died she hadn't wanted to carry anyone else's children.
"I'm the other way around," said Mei one day when they were drinking. "I want children -- and I ought to continue my bloodline, anyway; it's a husband I just don't want."
Neither one was drunk enough that the slip of confidential info was accidental. It was an opening, carefully calculated.
So was Mei's long, considering side look to the line of Tsunade's throat, the prelude to a dance of seduction Tsunade had never been on that side of.
It made her laugh.
"You'll have to carry it," she said, cutting straight to the chase. "Menopause, you know."
Mei chuckled low in her throat, painted lips curling. "Amusing, that a healer of your caliber could do away with the need for a male, and yet..."
"And yet," Tsunade agreed, though she might have managed to work past that, if she'd wanted. She thought Mei would like it, flaunting her unmarried pregnancy in her advisors' faces, because even in the stricter Mist society, who could say to her face that another Kage was too low-caste, a misalliance? "It'll be a girl."
"That's fine with me."
The conception itself needed a laboratory, not a bed and satin sheets, but Tsunade allowed Mei to lead her to hers anyway.
It wasn't anything like being with Dan, and so she could let herself like it.
Terumii Keina was born two weeks early -- the stress of cutting a swath through the remnants of Madara's old guard. Tsunade didn't intervene in Mist's internal affairs, but she was at Mei's bedside when the assassins came, and in between an eyeroll and a diagnosis jutsu she found some time to slam a few of them through the hospital walls, which left a lot of holes for Keina's first scream to ring through.
Even born a little early, Keina was a beautiful, healthy, stubborn baby.
She didn't feel like Keina's mother. She felt more like an aunt. Keina was Water Country first, and Tsunade had designed her genes to carry the bloodline limits of her mother, which would never be allowed to belong to another village.
She'd gone very far for Dan's niece, though. She could hardly do less for her own. She'd have to stay, of course. To remind the child that Konoha was also family.