The last enemy that shall be destroyed is death.
And that was exactly what Lily swore to herself, while making the last preparations to ensure her child would hopefully live through the madness fate seems to want to throw its way.
Of course she knew about that blasted prophecy.
Divination be damned if she would let her precious little one be a pawn to anything.
Fate could, for all she managed to care, go play with Moony on a full moon.
"The one with the power to vanquish the Dark Lord approaches... Born to those who have thrice defied him, born as the seventh month dies... and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not... and either must die at the hand of the other for neither can live while the other survives... The one with the power to vanquish the Dark Lord will be born as the seventh month dies…"
And there lies the crux of the matter. Not that she cared, she had a plan for that.
With the final preparations to ensure that this madness did not take hold done in secret, because she really did NOT want to have this discussion with James anytime soon. She just hoped her contingency plan would never be enforced.
It was for naught in the end, how he found them while under the fidelius made all sorts of accusations seem possible, but for them, that was neither here nor there.
James died some seconds before shouting for her to run.
Not really feasible, really, being in the second floor, under fidelus and external Anti-apparition & portkey wards up.
And she did not really have the time to go for the brooms in the hallway, neither did she want to leave her precious child alone any matter of time with Voldemort downstairs, surely already on the way moving up.
"So," she thought to herself, "it finally came to this then huh… alright!"
She checked around her one last time, made sure the runes where neatly covered by the rug and crib, and the ones on the wall hidden under the layer of paint and wallpaper on the wall.
All that was left was to give herself up for her light.
"Harry…" she sights, "i hope one day you can forgive me for this."
She gave her precious child one last peck on the cheek, stroking his head lovingly, while whispering a last goodbye.
He was wide awake of course, and clearly terrified. It tore her up from the inside to see her child in such a state of distress.
"Sorry" she whispers.
Getting that evil and vile man to take her life instead of that of her son was pathetically easy, him, blindsided by the bit of prophecy he overhead, and her in real distress and need to see her child live above her own life.
In the end it was the magical energy and surge in ambient magic around the already loaded room from his killing curse that set things in motion.
Fate has a cruel sense of humor.
The first was a discharge of all magic laid upon the child, forcing outward in every direction. The killing curse posed to strike got swept away in its wake.
The next steps would take quite some time to finalise, since many fundamental changes needed to be made, that were not meant to be changed.
The Dursleys had no close ties to the Potters since the drama they forced upon the marriage of James and Lily. So it should not really be any wonder that the gender of the child from her sister was unknown to them.
That Albus Percival Wulfric Brian Dumbledore chose an ungodly early hour to deposit the young Potter child like a neatly bound and tied present worked in saids child favour in this instance.
Between one and two hours since its graceful delivery to its new home, the real purpose of the willingly given sacrifice in love took hold.
Internal and external organs got shaped, changed and remoulded like Leonardo da Vinci would draw his newest Mona Lisa.
The end effect was a healthy and thoroughly changed child.
A girl.
And thus, Harry "Harriel" Potter came to be.
Not that the wizarding Public knew anything about it.
Or a certain Headmaster.
His monitoring trinkets, at least those bound with one drop of blood each from the child simply stopped working the way they were meant to be.
It was obscure magic after all, not really thoroughly researched.
They just continued to monitor the last known area said child was in, since it lost its target.
The trinket tied to the wards showed them stronger than ever. He was quite pleased with himself that his choice in the Dursleys was right in the end!
Not that he knew why they were at an alltime peak since years.
The book of entries also showed the change in status of our young protagonist.
But wizards are wizards.
Logical thinking seems abhorrent to them.
They never checked up on her.
And since the Hogwarts letters get sent automatically, and only in those instances where further persuasion is needed someone gets involved, no one ever found out.
Until
"Potter, Harry!" said a scottish voice, whom's owner looked frantically across the Great Hall in Hogwarts.
When a girl with dark-vine red hair, killing curse green eyes and no scar stepped forward, everyone went silent.
There were no whispers about a certain Harry Potter, boy-who-lived or other platitudes, since quite clearly, this was no boy.
Dumbledore finally gets a hold of his stupor and monitors for his deputy to go ahead with the sorting, needing time to sort his bearings.
...
"Ravenclaw!"
When the staff of Hogwarts meets at the same evening, and he presents his findings, reasonings and conclusions, it's quite the tale.
Lily Potter, upon hearing the Prophecy, concocted a final desperation plan to save the life of her child.
The Prophecy clearly states "... Born to those who have thrice defied him, born as the seventh month dies... and the Dark Lord will mark him as his equal, but…."
Severus, together with the resident healer Pomfrey, under the guise of a routine preliminary check-up, scanned for potions, charms and every other method they could envision. Discreetly of course.
Even all internal and external female parts are working as they should, wich no potion can achieve, and lies way beyond its practicality to uphold via charms and other methods. It is no glamour either.
So Lily Potter simply removed her child from the quotation concerning the Prophecy.
Petunia Evans, upon seeing the child, took it as a means to right the wrongs that happened between her sister and herself and grew out of her bitter resentment towards Lily and things magic.
The child was almost a carbon copy of her mother.
Upon visiting the Dursleys, they were a real normal family, no overweight, no grumbling and no hidden corpses or dark secrets strewn around.
The wards where blindingly strong, powered by the bond the family had with young Harriel.
Her life was by no means easy, and she and her friends got blindsided around the war concerning Lord Voldemort and Neville Longbottom, but managed to hold themselves on it's outskirts.
In the end, Lily got her wish of
"The last enemy that shall be destroyed is death."
Quite literally the only enemy her child would ever have to face in her life.
Hopefully with its head held high and a smile gracing her lips.