The Robinsons was a family who lived together for economic reasons mostly. You had the head of the family John Robinson the breadwinner father, then you had the wife Maeko Robinson and their kids Johnny Robinson and Amy Ame Saito both of them 12. In truth about 5 years ago John Robinson and Maeko Saito were next door neighbors and then the incident happened. There had been a lot of damage, and while the families were thankful that their kids survived John's wife and Maeko's husband died and their homes were wrecked. At the shelter there was a lot of talking, and since Amy and Johnny played together a lot and hung out the two widows ended up discussing a few things and... Well after looking through all sorts of financial and tax data and how their insurance plans were working... They got married. They both weren't over their spouses that quickly, but it was a marriage for financial reasons and a bit for stability in a sense. With their insurance payouts and savings if they pooled their money together they could easily afford a house. Their kids liked each other, and so many other potential benefits. The adults mostly treated each other more akin to roommates with maybe some benefits in sharing chores, and making it easier to look after the kids.
5 years after most of the cleanup had been done, emotional trauma settled, and the adults were keeping a bit of a closer eye on their kids as they were entering puberty. The two kinda had a siblingish/best friends relationship going on, but... couldn't be too careful. The transition from next door besties to step-siblings was shaky but they came out alright. The parents wondered if the two developed deeper feelings if they should stop it... they started out unrelated, they were unrelated... it'd probably be weird if they became lovers right? maybe? The families weren't really that married, the marriage was more of a bond of trust than love or lust.
The anniversary of the tragedy was coming up and the little shrine that had the portraits of the lost parents was getting dressed up again. It was Maeko's idea, and John fully supported the idea as a way to keep them in memory. They'd pray, mourn, have a large dinner together, and they felt more like a family on those days. It was still a couple days away though, and that gave enough time for Trans-Diem to do one of their randomized beta tests as the chronivac landed in the hands of the family... but whose?