They turn out to make a really excellent team. They want the same sorts of things. They have powers that work in similar, companionable ways. Somewhat hilariously, they even have blessing sets that work extremely well together. ("Danger sense and a resistance to panicking, both - I don't think we could have planned that better unless we sat down after starting and working it out," comments Tisvetaia.)
More holy objects are exchanged to bless each other's mortals. They bless each other. They bless and poke people they meet in Milliways, often taking different sides of the bar to cover more ground and informing each other when they find someone who could use some blessings or pokes of a specific kind. And sometimes the bar is empty, and they can keep each other company and talk about how their domains are doing.
During one of these moments: "It strikes me that you could send a couple animal manifestations to my domain, to spread and collect disease immunities. I already have a system set up for people petting animals for immortality, my mortals will adjust pretty well to it, and obviously we can just coordinate as we like. I don't think my neighbors will mind."
"I'd like that," says Kirovalin. "You could do the reverse, too, but I have a lot more people to cover than you do."
"Just a bit," she snorts. "But I'd be happy to. I could get your advisers and acolytes for sure."
"I try," she says lightly. "Give me a little while, I'll send some critters over and open the door for them when they get here."
After a span of time, her animal manifestations arrive, and she opens the door for them. They are birds, because flight is handy.
They're very large. Not outrageously so, but definitely in the top tier of ordinary bird sizes.
In they get to go to her domain!
Her domain is nice. It's warm and fertile (which is unsurprising, since she's a volcano goddess) and her temples accept people in need and provide them with food and lodging and if they would like, something to do. She gets along with the established mortal government (and has a habit of prodding the nasty members of it to get them to stop mistreating their people, and blesses those who are good...) and makes a habit of making it clear that if people would like to talk to her they can address her directly. She organizes regular immortality poking rounds, of which she neatly incorporates Kirovalin's birds into.
His population is very pleased about this cooperative effort of his.
That is to say: Three hundred million people discover Tisvetaia's existence and are pleased about it.
There are some things she loves more than the rush of power from lots of people thinking about her, but it's not a long list.
There's only one thing to do in response to that, isn't there? Make more birds, obviously, and cover more of Kiro's domain, and distribute lifespan extensions more thoroughly. Whee!
(Also expanding her domain a bit and maybe adding more to her efforts to make that decay god neighbor of hers go away, and add another human manifested form or two to run around and poke more people outside of her domain...)
A few months into this cycle, Kirovalin says: "Some of my advisors have suggested I raise a seventeenth province out of the ocean and turn it over to you."
"We are likely to need some expansions to deal with extra population," she muses. "Ultimately part of your empire but technically under my control and general authority, prod you for major problems or things I don't know how to handle? It's not like I have practice ruling mortals. I'm not unwilling, mind, just - logistics and organization structure are important."
"I'd appoint a human governor to start with who would answer to me on matters concerning the empire as a whole, but you would be the local source of divine intervention and the local authorities would answer to you on local matters. I can take your manifestations on a tour and show you some of the uses of power that my citizens expect of me, so you know what you're getting into. You could decide later whether you preferred to take over the governorship or leave that in mortal hands."
"The tour sounds good. Baby's first province, and all, I wouldn't want to be a lackluster god."
He describes upcoming public works projects to her: routine adjustments like managing the water table and boosting crop growth in underperforming areas, rarer interventions like altering the course of rivers, things rarer still like creating veins of ore to be mined - if 'mined' is the word when all the mortals have to do is come chip it out of the walls of caves. His people know that they can petition him for these things and be pretty sure of getting them if they put persuasive enough arguments or numerous enough supporters behind it.
Once she has a good handle on what sorts of things would be expected of her - she happily accepts.
Kirovalin expands his domain under the ocean in the chosen spot and raises a large island, comparable in size to the neighbouring province of Navehneni, which is also an island of its own. The size isn't arbitrary; he makes sure there is room for every citizen who wants to settle there immediately, plus more space to expand into later.
And then he unclaims the island and lets Tisvetaia move in, along with shiploads and shiploads of mortal settlers.
She's organized, efficient, and she pays attention. She notes that Kiro's citizens aren't used to warmer temperatures, and keeps the province purposefully colder than her original domain. It's still noticeably warmer than the rest of the empire, but not so much that the citizens are uncomfortable with the shift. She has an easier time with farms and fertility, as well - she doesn't have to fight with temperatures and her soil naturally is very rich. She manages the water table and watches the crops and tends to send gentle rains during the night to water them when necessary. She adds little interesting fruit trees to the islands and small fuzzy creatures that everyone agrees are adorable and make excellent pets. She sets up hot springs with little stairs already carved up the mountain (technically a volcano, but she'll never erupt). She has her manifested birds subtly preserve buildings (to resist rot and the like) and works out where roads are going to go with the governor and then makes them herself.
She obviously enjoys herself a lot, and works very hard to keep citizens happy.
Time passes, and passes, and passes some more.
When Tisvetaia has been overseeing her province for a little over a year, a new set of coins are struck at the Imperial Mint. Instead of Kirovalin's face on one side and his bird form on the other, they have Kirovalin and Tisvetaia on both sides, human and bird. The old coins are still valid, but all new ones will follow the new style.
"That," says her manifested form in Milliways, once she's recovered, "is atrociously adorable."