At the End of the Rainbow
Severus stood in Dumbledore’s office and stared at the wailing baby, at the plump cheeks, at the small button nose and at the shiny black eyes. His eyes.
And although he knew he was horrible and unresponsible and absolutely unsuitable for the task he had set his eyes on, he knew he couldn't turn away.
For this was his child.
Or:
Severus Snape hadn’t told anyone about the little adventure he had had in the summer before seventh year. Said adventure had included a feisty muggle girl named Milly, cheap beer and a chilly summer night on the bank of the Cokeworth river.
Severus hadn’t heard about Milly after that, and he assumed he wouldn’t, ever again.
But then he does, mere months before he is to take the Mark.
He has a daughter.
A halfblood daughter.
Whose mother is a muggle. And dead.
And now Severus – somehow, some way – he can’t even begin to comprehend the exact details – has to navigate between the Slytherins and the Death Eaters and the Marauders and the war and the knowledge he has a child – a baby whose life is comparable to that of an earthworm to those whose company he had intended to join mere hours ago – and he – he just doesn’t know what’s what anymore, he doesn’t know what to do or where to go, but he knows one thing.
He will do anything to protect his child.