I suppose a part of it went during my second year when I was turned to stone. Bits and pieces went as the war escalated and significant part went some time after Dumbledore died and before Harry was killed by Voldemort during the Hogwarts disaster. Belatrix held me under cruciatus until I stopped twitching and left me, legs trapped under a wall, to slowly burn, wand just out of reach.
The Ministry eventually got around to sending aurors to Hogwarts. Some time after the fires started to die. Amazingly the fiendfire somehow missed a small portion of the first floor. It still passed close enough to burn my back, all my hair and the right side of my face.
Innocence, what a strange word, but to me it was important: it was a secret, quiet joy that filled my waking minutes and waited impatiently beside me while I slept, blissfully unaware of the cruel vicissitudes of fate. I was so full of life.
Last sliver of it drained six months ago with my blood as I carved the runes into my skin and opened my veins. Amazing, the things the owner of Grimwald place can find in it's library. Apparently the dead were not affected by the killing curse.
I had no idea Harry even had a last will.
Now, I only know that whatever happened to me, I'd rather die than allow what happened to me to happen to another child. It is this drive alone, this fierce determination to protect the world from what I have become, that allows me to face the dread of waking up again. For until my purpose was done I would wake.
Most of the Death Eaters are gone now as well as some in the Ministry. Eaten in turn by a gaunt, almost skeletal form in a black robe, immune to all magic, surrounded by shadow that drained all magic inside it. After A while I vent and bought a scythe just for the hell of it.
Tom is covering behind his fading wards as my shadows eat into them. I hold the last dose of my blood in a cup with a badger symbol on it. Just enough to keep me undead and sane for one last day on this earth.
And so, Fate, a toast to you. To the loss of innocence.
It shall not go unpunished.