A Well-Prepared Revenge

An eidetic memory of every moment from birth is a terrible gift to have. Especially when some specially-treated parchment and a record-searching ritual confirm it:

Without a name, barely after even being born… she rages.

She sorts into Slytherin, because of her unusual…ambition and her desire to pursue it, no matter the cost. She survives, because she must.

She worms her way into Harry Potter's circle. After all, is there anywhere better to hang around if one wishes to attack a trio of Death Eaters, given he'd be a target if they did get out? Even though she couldn't care less about them being Death Eaters, it's the best lead she has.

When she discovers the Room of Requirement in second year, things begin to get serious.

She prepares. The Room of Requirement's bounty is focused on her single goal.

She devises spells. One is essentially the Draught of Living Death in spell form, except it keeps the target somewhat aware and potentiates the effects of other spells to last for its duration. Another is a spell which looks like and feels like the Killing Curse, but is actually completely different; instead of detaching the soul from the body, it makes the body fall apart; instead of ignoring all magical barriers, it ignores all physical barriers—a deceiving killer. She masters casting them until she can do so both wandlessly and wordlessly—not as an exercise, but as a necessity.

She makes a bolthole and a portkey to it. She creates the wards shielding it from the Trace and suchlike at Hogwarts, moving them into place later, before using those wards to build the rest of them. She disguises her portkey as an ordinary item, one not worth sparing a second glance at, not even in a duel.

She learns to fight. Not to withstand grueling duels, because she knows that isn't what she's aiming at, but how to be invisible before making the first strike and how to dance around the attacks of others while focusing on her real targets. She doesn't need to win entire battles by herself, she just needs to kill two people and incapacitate another.

In her fifth year, she smiled when she learnt that her targets had escaped from Azkaban. After all, they were now within her reach and, given her association with Potter, would almost certainly be in a position when she could attack them.

She sharpened herself more and practiced her crucio.

In the Department of Mysteries, she ignores absolutely everything until she sees Bellatrix. A whispered crucio alongside a wandless spell traps her target in ceaseless agony. She grins wickedly and stares at Bellatrix until a flash of recognition appears in the tortured witch's eyes. That ought to pay my excuse of a mother back for her spinelessness, she thinks. But she doesn't linger long enough for anyone to move against her.

She turns towards her remaining pair of targets. Accio the Lestrange brothers' masks, she casts. Using that disturbance to identify her targets, she hits them with a pair of wandless curses. Looking for all the world like the Killing Curse, the duo conjure concrete barriers to block them. They don't realise that was cast wasn't the Killing Curse until their skin, muscles, bones, and organs begin pooling at their feet.

Not bad for someone who's effectively a mudblood, is it? she says as the Lestrange brothers begin to die, while her mouth twists into a chilling smile. But I think my life's work is done now, not-so-gentlemen, so ta-ta.

She activates her portkey and vanishes.