I just came up with a crazy fic idea hear me out:
Reader saves old Sun and Moon. Biblically accurate designs from the fire and keeps them in her home.
The new separated Sun and Moon are built months later, more like androids and more human in design. Reader is called back to work, but now has to deal with four Sun and Moons to juggle (two at home and two that don't know the reader yet at work).
Reader is a badass. Biblically accurate Sun and Moon are also badass and definitely damaged and terrifying to any normal person.
Reader does a video call with new Sun and Moon while at home, and her old Moon peeks into the camera, causing the new sun and moon to scream bloody murder because "WTF IS THAT ITS EYES ARE RED IT HAS SHARP TEETH ITS MISSING HALF ITS FACE IS THAT THE OLD MOON EITH THE VIRUS THAT KILLED PEOPLE!?"
And Reader calmly tells them that her old Moon is just a big spooky metal baby. Cue the disbelief.
Biblically accurate Sun and Moon are horror based, damaged from the fire, and still have remnants of the virus. But the reader doesn't mind at all and adores them both all the same. The old Sun and Moon are frighteningly tall, but the new Sun and Moon are separated and short like the standard human would be. Naturally, the new sun and moon would be horrified to find the sweet reader housing the nightmare bots in her own home without worry.
Cue new Sun and Moon realizing that the reader is actually a badass and has way more going on then meets the eye.