I saw your Kaguya post and I kinda have a bit of an au in mind where tenji sided with her out of love, but it doesn’t end well for him.
Huh. I...haven't really talked about Kaguya for a hot minute. Mainly because given what little material we have I was afraid of letting my headcanons run riot or just the nervousness that comes with discussing a hated character you enjoy.
But I digress.
Anyways, Tenji.
Understanding an AU like this obviously means understanding what their relationship was in the show. In the show, Tenji DID harbor feelings towards Kaguya. Obviously. He was taken in by her beauty (who wouldn't), took her as a concubine, and fathered her children. Course, there's indications that they weren't that close since he only talks with her the one scene and then decides to order her execution in order to appease a rival faction.
But let's assume for a moment that Tenji refused to betray Kaguya. Maybe he actually got closer to her in canon and her desires for peace softened his "execute anyone who provokes the rival country" stance and possibly look for an alternative solution. Perhaps he saw her more as a person than some godlike monster that she was seen as in the episode. And when Suzaku rats her out (the same prick who tried to kidnap her and do lord knows what) for killing in self-defense, Tenji decides not to execute her.
It...probably won't end well.
Suzaku would use this as grounds to invade the Land of Ancestors for harboring a demon. Mind you, this is presumably a fight Tenji can't win since his ministers were talking about fighting to the death since the odds were that against them.
This is where Kaguya steps in.
She mentions that for all of them to have a chance, she NEEDS to eat the Fruit of the Divine Tree, giving her the strength to take down the invaders. Again, she probably still has a lot of the old Otsutsuki doctrine instilled in her, but in this case it might be their only shot at survival.
There's just one...minor problem.
She's pregnant.
Like in the show, she probably can't defend herself when she's going through pregnancy pains. Which...could lead up to that tragedy you mentioned. Instead of Aino sacrificing herself to save Kaguya, it's TENJI who stands his ground and buys Kaguya enough time to recover and make a beeline to the Divine Tree.
Which in turn, Kaguya is able to eat the Divine Fruit and become the Goddess of the Shinobi World.
So, where does this leave Kaguya? What consequences will Tenji's sacrifice have for her? Well, I find it doubtful she's gonna change overnight. Again, it's hard to immediately throw off beliefs that you've grown up with. But I could see her being a bit softer on humanity. Perhaps not relying on draining people's chakras via the Tree so much, maybe not cast EVERYONE in an Infinite Tsukuyomi. There'd still be sacrifices, but perhaps they won't be as bad as in canon.
As a whole, while Kaguya would still have issues with mankind (I mean, it was their conflict that took Tenji after all), I can see her being a bit more reasonable and possibly being less of a tyrant. Where it goes from there is up to you.