In the end, the tree house had been a really good decision for all parties involved.
1. Regina, who got a huge hug from Henry for her efforts; which involved the actual use of power tools since she didn't trust Henry nor his incompetent-with-all-things-sharp-and-pointy biological mother.
2. Emma, because using said power tools involved sweating, and the Madame Mayor couldn't very well sweat out a tight pencil skirt and blouse. So she'd opted for a pair of shorts and a dark brown sleeveless shirt. And since Regina's decision to not let anyone but her touch the power tools, Emma mostly got to hold the ladder. Underneath Regina. The amount of times she's wanted to throttle Regina and the amount of times she's been more than warm in places she doesn't feel like thinking about was a high and nearly balanced ratio. The kid's smile was pretty darn rewarding too.
3. Archie, who'd stumbled into the family moment by accident, but was allowed to stay because Regina relented and accepted help as he had some experience with power tools.
4. And Henry, who finally had a place to hold secret meetings with his new friends. Friends were nice, even though real ones had been hard to weed out after everyone found out he was Snow and Charming's grandson. And his mother hadn't used any magic to build the tree house. And he had his other mother, who wasn't stuck in a post-apocalyptic Fairytale Land anymore.
In the end no one was throttled, Regina may or may not have smiled at Emma once, and there was only one disaster with the power tools. A minor one. And only because Pongo had raced in, grabbed a box of screws, and raced out before Emma could say any colorful language Regina would probably have gut-punched her for. Or verbally gut-punched.
In the end Archie, (who had frantically rushed in to catch his runaway dog) ended up getting the treehouse finished in a much more timely fashion. Regina still got the satisfaction of screwing in the last bolt. When she said this out loud, Emma had risen both brows separately and with much amusement.
In the end the entire group sat with a tub of ice cream and a large amount of pillows inside the newly built treehouse, (all wired in with a television, a radio, and access to the house's wifi). Regina and Emma fought over who would serve it:
("Seriously Regina your scooping skills are mediocre at best; some of us actually want more than a fancy restaurant-sized portion."
"Well, Miss Swan, some of us actually want to maintain good health and get a good night's rest.")
Emma won because everyone chooses large scoops of delicious ice cream over their health (much to Regina's chagrin), a movie was watched on the tv (Enchanted, Emma thought it would be hilariously ironic, the result from that was a much larger than restaurant-sized scoop of ice cream ending up in her hair), Archie was mostly uncomfortable throughout the whole ordeal but was pleased by both of his patient's apparent progress, and the cramped space had somehow resulted in Emma's head half on Regina's lap, both asleep as starlight shown through the (slightly lopsided) window.
In the end, Archie slipped down the ladder with a quick goodbye to Henry, and Henry could hear Pongo's cheerful barks as Archie came down to greet him. Archie thought about his quiet observations of Regina in this new element, where the void magic had left in her was slowly starting to be refilled. She deserved redemption, and he was believing his own opinions more and more day by day.
In the end, Henry had looked curiously over at his sleeping mothers, noting how his mother's hand seemed to settle on top of Emma's hair as the latter slept peacefully half on top of her thigh. He knew their position was likely to shift, but it was such a perfect moment, so serene, so devoid of any of the heartache experienced in the last few months. It didn't matter that he hadn't quite forgiven Regina, that Emma hadn't quite forgiven Regina, that there was always some sort of elephant in the room of their entire current existence. It didn't matter, because a tree house was built, and for a few hours they had been…something. Not quite a family, but definitely getting there. The warmth of a family. Maybe a family? Could Regina Mills and Emma Swan co-exist peacefully? A year a go he would have said no way! Because good cannot live with evil; good has to triumph evil. Now age has made him see his own flawed logic. His comprehension of that so vastly blurred line grew and grew. Much was still muddled but one fact was certain; neither could exist without the other.
It was a fight between Regina's entire history with Snow White, and Regina's hand still on top of Emma's hair, and Henry wasn't quite sure yet who won. Maybe it didn't really matter. But there was a certain harmony in the day; like the last piece of a puzzle being fitted into place. He wanted to repeat it, wanted the mundane of the rest of his life to have the same harmony.
And a plan was, of course, already forming in his head.