He is there:
--
When the boy is born.
He holds him, says he looks healthy. Grins like a fool when the little fingers wrap around his.
He stays for half the year.
--
When he turns three.
He picks him and grins when he tilts his head and says, "Da…?" He bought him a plastic rocket and goes on about inaccuracies and inefficiency and Mother nearly screams when she sees him. (She does scream, later, screams abuse at him when the boy is asleep until she begins to sob. He leaves then because he doesn't want to be there when she stops.)
--
When he is ten and three weeks.
Because he missed the birthday – not forgot, he insists, but missed – and it's not every day a boy turns ten. He gives him a football, saying some form of sporting equipment is a traditional father-son gift, at least on Earth, and tries to hide his excitement when far more interest is given to asking how the sonic screwdriver works. He has him guess, grinning and shaking his head at what would be reasonably logical theories for something of this world.
The screen door creaks on its hinges, and he can't quite get out of sight quick enough not to hear the strangled cry that follows.
Mother is sure she is breaking.
--
When he is seventeen.
It is late and the living room is lit only by a dying fire. He doesn't even have a chance to greet him before pain flares up in his cheek.
He rubs his jaw – not surprised, but discouraged. "Good arm, son," he says, and the boy punches him again, harder.
"Get out. Stop coming back." The voice is uneven, shaking with the effort not to scream. The last thing Mother needs is to wake up and see this. See him.
He frowns and leaves without another word.
--
When he is twenty.
Same house, same living room, a boy who is barely a man already looking world-weary. No violence this time, just an old look of loathing softened into some form of acceptance.
The words he no doubt meant to speak three years ago (at least it was three years to him) float enticingly around him.
The things you'll learn.
Not your world.
Time Lords.
He looks at his father – unaged, eternal – and knows he can't do this anymore.
Mother wakes up to the sound that plagues her nightmares, runs to the living room. But only an unnatural breeze that sweeps at her hair and bites at her eyes remains.
She falls there, and never quite gets back up.
--
They are there: no longer.