Po 15 července 2019
Originally published as “Harry & Ginny are brother and sister” on Reddit.
I see it like this. Lily was already pregnant with her second child (it is slightly over a year between Harry and Ginny so it is biologically possible), when they found out about the Prophecy and need to hide. They've agreed to hide Ginny with Weasleys' (no, sorry, their anti-girl-curse, if there was a one, has not been broken then, and yes it helped Ginny was a natural redhead after her mother), which they did slightly after her postpartum period (that is after September 22nd). All Weasley boys were memory charmed to have included their Mum being pregnant again (which, frankly, was not that difficult charm to make, because everybody remembers her being pregnant all the time ;)). Then Potters started to work on preparing place for Harry with Dursleys, but they have never managed to finish it and they never told Vernon & Petunia, before they were killed on October 31st. Which was the reason why Dumbledore put Harry with Dursleys (he actually never really understood the mechanics of those blood wards, because they were Lilly's unfinished invention, or something).
These two will find out only when told in Harry's fifth or sixth year by Dumbledore, who sees a danger of upcoming incest.
Now, it gives us a nice setup for non-Hinny ship which doesn't need anybody's bashing. Or even Ron/Ginny ship, if anybody cares about that (but that's not probable, due to the Westermarck effect).
What do you think? Is there such a fic based on something similar?