Disclaimer: All recognisable characters are the property of JK Rowling.
The Weight of History
He sits, utterly exhausted, in the chair before the Headmaster's desk, willing his spine to remain straight as his muscles scream their mutiny.
"I understand your fears, Severus, your uncertainty. The boy is important, more precious than you could have intended him to become, to you. Do you see now, Severus, why I do not wish for Draco to be damaged by the act of murder?"
Finally, he finds his voice, and struggles to contain his anger.
"You, Dumbledore? You deign to speak to me of care, of compassion, of my desire to keep Draco safe? While you have sculpted the Potter boy into your plan, crafted him into a selfless martyr, all for your cause? You have no real care for either boy! Your only wish is that they fulfil their part in your master plan!"
Dumbledore's eyes turn suddenly livid, wild with rage, and he sweeps across the room to seize Snape's robes, shaking the younger man as if he were nothing more than a misbehaving child.
"You cannot fathom the depths of my concern for these boys! For the children cast under my care! It is for them, only them, that I have asked you to risk yourself! It is the defeat of your Dark Lord I desire, so the children of my school can live freely, without fear!"
A sickening doubt rises in Snape's gut, and he is no longer intimidated by Albus Dumbledore.
"Is it the fall of the Dark Lord you desire, Dumbledore? Or is it the defeat of the memory of your failure? Of your foolishness?"
The old wizard releases his grip on Snape's robes as if they are scalding, his face etched in shock and awe. They stare, frozen still, until Dumbledore finally, fatally looks away.
"I will not deny it, Severus. Perhaps... perhaps it is my greatest desire, to erase the fatal errors of my past. To cleanse my history in flame and fire, and death."
Dumbledore is so prodigiously skilled at manipulation that Snape finds himself feeling guilty, repentant, and nauseated.
"No-one in this world is free of secret motivations, Albus."
"No. We must do what we can, and hope our reasons will not outweigh the good we have done, in the end."
"For the greater good? For the greater good we will sacrifice Potter, Draco, our own lives? Do you suppose Draco's mother believes in the greater good when she casts her only son into the arms of the Dark Lord?"
"Narcissa Black made her choice, Severus. She chose her loyalty, as a young child. As did you-"
"And what choice did we have, Dumbledore? When we were gifted, by fate and arcane ritual, to futures forever in shadow? What good can a child Sorted into Slytherin achieve, when they must do battle against the very weight of history?"
"You have chosen to do good, Severus! You have chosen to love, even when the ones you love have chosen others! You have been devoted to a memory, to another man's wife, and look at the good you have done, and that which you are yet to do!"
"And to whom are you devoted, Albus? Whose memory do you serve?"
The old man looks away, his gazes falling upon Fawkes, in the throes of death upon his wooden perch.
"I have no-one to serve, Severus. I have not been as fortunate as you."