Disclaimer: Everything you can publicly recognize is not mine.
Summary: This isn't the first time Elena has hurt Damon, but it is the first time Serena Mikaelson helped him forget. Even after snapping Kol's neck, Serena helped him and the next morning, Damon escorted her out. But the next day, Damon is drawn to Serena again and things just kind of progress from there.
Prologue
Serena Mikaelson.
Once, that name struck fear in vampires' hearts. It made her almost as fearsome as Nik himself.
She was a bloodthirsty bitch that only obeyed Elijah and Niklaus. Everyone else? They could be damned.
She turned millions of people, along with her twin Kol. They travelled together, experienced life as no one else knew it. Experienced the blood lust and power, and sometimes, even mercifully left the humans they had drank from survive.
She wanted nothing to do with doppelgangers, and thus, she never met Katherine. At the time, Kol and Serena were travelling in Europe, as far away from Mystic Falls as possible.
But when Niklaus caught up with them and daggered Kol, both Kol and Serena felt the pain of the dagger once more. They felt the cold numbness travelling up their veins, reaching their pumping hearts, one which was crossed with a special silver dagger. They both closed their eyes when darkness consumed them and they barely felt their body fall.
And that was how things came to be.