This was written pre-OotP. And is therefore AU.
One man's dream

Harry Potter once asked me what I see when I look in the mirror of Erised, and I must confess I was not entirely truthful. The real story -well, I will tell you.
I am much, much older than people think. The truth is, dear old Nicholas Flamel was a childhood friend of mine - he was in the same year as me at Hogwarts.
When I was about twenty-six, I discovered a way of becoming immortal without having to drink the Elixir of Life once every few months. The only problem is that once you have done it, there is no going back, that is why I have never told anyone how to achieve it. With my method, you could be gravely ill, you could come within an inch of death, but never actually touch it. I was young and foolish, I thought myself marvelous, I never thought about the consequences it would bring.
I never told anyone about the fact that I am immortal, apart from my dear friend Nicholas, for after about three hundred years, he began to inquire why I was still around.
Shortly after my success with immortality, I fell in love with Morag Gryffindor. She had lovely black hair, chocolate brown eyes and a warm smile. She was an heir of Gryffindor (hence her name), and so was I, though the relationship was very distant. About a year after we met, we were married.
We had five children, Mark, Morgana, Yseult, Guinevere and Eleanor. Morgana married a Weasley, (I feel sorry for blessing that family with my auburn hair, though I think it has changed color slightly over time!), Yseult married a Longbottom, Guinevere married a Potter and Eleanor married a Malfoy. It is strange; in those days the houses of Hogwarts shared a little good-natured rivalry, but none of the full-blown hatred we see today. Then everyone knew that Lord Salazar Slytherin didn't like or trust muggles because his own mother was killed by witch hunters when he was barely five years old, but that has worked itself up into the belief of some people that muggles are inferior, the real reason has been lost in the dregs of time.
Of course, it was too good to last. Forty years after we were married, Morag died, and I was left with a burden of grief on my heart.
By then, all my old school friends, and many that I made after I had left school had all died, except Nicholas and Perenelle. It was when the eldest of my children, my son, Mark, died aged 71, leaving behind a daughter and a son, the harsh reality struck. I realized that I was going to live through generations of my descendants and I would never join my loved ones. I think that my grief unhinged me slightly. I passed the years observing from afar the rifts growing between my descendants. It was rather amusing actually. The Longbottoms, Potters, Weasleys and Blacks (Mark's son died without children, and his daughter married a Black) all grouped together, but the Malfoy dynasty went on alone. It was always like that when they were children; Eleanor was always on her own. I think these great dynasties have all but forgotten that they are descended from one man. Then, a short while ago, the remains of my childhood were torn away from me, and now I spend a great deal of my time searching for away to be mortal again. I think I will leave behind a book, telling how these last descendants of one brother and four sisters came to be so divided, and to forget their families' histories. So, when I look into the mirror of Erised, I see my Mother and Father, my brother Aberforth, Morag, Mark, Morgana, Yseult, Guinivere, Eleanor, Nicholas, Perenelle and all the rest of my childhood friends standing around me.

But I would not lie completely to Harry.

I do see myself holding a pair of socks.

A/N: Well? What did you think? Review, don't flame me. I won't say this is the best story I've written, I am in the process of writing one about Sirius that promises to be much better. I wrote this ages ago.