Dear grandfather.

I am Gallifreyan,you know. I can sense what happened.
I'm sure you have your reasons. I'm sure that if I let you talk, you'll be able to prove that the blame lies elsewhere. I'm sure that if I let you work your little magic, you could talk me around.
Well, not this time.
I knew about the war. Everyone knew about it, but few others understood what it meant. I saw you at the heart of it, right from the beginning. Don't try and say that you weren't involved. It was your interference that started the whole thing.
How did you do it? How did you manage to kill every single other member of our species and survive yourself? You must have had help. You must have manipulated an army into fighting for you, never touching a weapon yourself because you 'will never take a life unless another is threatened'. I know how many died, grandfather. I felt them go silent, and I'm sure you did too.
It was a safety net. The constant murmur of billions of lives in the back of my mind. I might not have been connected to the Matrix, but I could still hear them. All of them. And I heard it when they all went silent. All except for one old man. You.
I don't want to hear your excuses. I just want you to know this.
It was my planet too. We fled because of you. If it was up to me I would've been able to go to the academy, I would've been able to graduate and I would've gone on to do something great. Instead, I'm stuck here, on the other side of the universe, and I can't get home because my home is gone. All I can do is sit here with my husband, who I have to lie to, and my adopted children, and watch them grow up happy, and I have to try and laugh when they smile even though all I want to do is cry.
I'm sure it's something you're used to. I know you did it to me, sometimes, saying everything was fine when the truth was as far away as you could get. Do you still do it? Do you still bother trying to fit in after you committed double genocide against the two most powerful species in the universe?
What happened to them? How did you kill them?
Actually, I don't want to know. I don't want to know what happened to that old planet with its twin suns and long red grass and the old house half-buried in the mountainside. I don't want to know how you are still alive and I really don't care if you've found a wife and you've settled down on Sontar with a small army of children. I would pity your wife, but I don't care about you.
I don't want to hear from you again, Theta Sigma. Don't bother replying to this letter. I'll never read it. Just leave me alone to get on with my life with David. He's fine, by the way. Thank you for asking. You could've come through once, just to check how I was doing. But you didn't, and you know what? That's fine. I don't think I want my children to look at their great-grandfather and know that they're related to a monster.
Farewell, Theta Sigma. We will not meet again.

Susan

If it wasn't for River Song on the other side of the room, he would have jumped into a dwarf star the moment he had read it. Luckily, River was able to convince him to stay.
River killed him a day later. Forced to. He guessed that there had to be irony in that somewhere.
He was too busy to think about it after that.

The man who regrets and the man who forgets.
He's the one that forgets.