Wouldn’t it be fun, in the Hunger games, if Katniss and Peeta was actually brother and sister??
Katniss and Peeta’s (And prim’s) parents divorced, and Peeta went with their father while Katniss their mother, so they have different last names and come from different parts of 12.
They know, their parents know, Prim knows, and no one else does.
Peeta still goes with the “I’m in love with her” route, and Katniss just sits there being all like “I’m sorry what????”
Katniss is the elder or the twins (since they are of the same age) and gets quite protective of Peeta in the games, though the kisses are very awkward.
Gale knows as well, and instead of jealousy he is just infinitely amused.
During the tour they tell Haymitch and Effie, in which one toppled over of laughter and the other just stared into infinity regretting everything. Guess who did what.
When they try to tell Cinna however, he just smirks and whispers a “I already knew”.
The idea of marriage is quite sad for them both, as Katniss herself was in love with Gale and Peeta always wanted to find love on his own, settle down and have a family (possibly with that handsome man from District four, because I’m definitely going to throw some gay shit into this you know me).
Haymitch has a problem not bursting into laughter every time someone brings up the so called baby.
Johanna figures it out “Your noses are quite similar”, and Katniss suspects she told Finnick as he smirks a little every time they kiss (and Katniss notices that he openly checks out Peeta during multiple occasions).
No one else figures it out though, as Haymitch strictly tells Katniss not to tell 13 about what’s actually going on.
In the very end, they get “married”, with Katniss marrying Gale in secret and Peeta mourning over Finnick together with Annie.