I mean... think about it. Who does Banquo love the best after his son? Who does he trust the most, and confide in, and tell endless stories of to his wide-eyed son? Who would be the most important person Fleance would know to run to, should anything go awry?
He's maybe 12, coming back to the palace with his father after a long ride, all pink cheeks and tired but happy, and still thrilled that his father is the closest friend of the new king, and they're staying at the palace now. He takes the torch to light their way down the path from the gate, because he always carries the torch for his father.
His father remarks there will be rain tomorrow.
And then the rush, the torch knocked from his hand and gone out, the scraping of steel as his father tries to draw his sword, and Fleance reaches for his dagger, but the shadows are hulking and his father is shouting over the attackers grunts and complaints. "Fly, fly, fly!" he cries, and the boy obeys.
He knows who to run to for help, he knows who he can trust. He knows how brave and fierce a warrior Macbeth is. So he runs, small and slim, and sure-footed even in the dark.
He does not hear the death gurgle, though his own fear chokes him, knowing his father is probably dead, hoping with the wild hope of youth that Banquo can fight, can fend them off long enough, until Macbeth should come. He doesn't know how many more attackers there might be, he can't be sure they won't come after him. So he skitters off the path, weaves through the trees, trying to remember where the side entrances are, thinking he should slip in through the kitchens. He can't trust anyone until he gets to Macbeth, until Macbeth knows. Macbeth will protect him.
So he slips and he sneaks through the dark, through the doors, taking the round-about way even if it's longer, moving fast, thinking forward, only ahead, not back, he can't think back, not now. There's a feast on, he and his father were supposed to be guests of honour at it. But now the food smells make him nauseous. He skulks through the shadows of the scullery, catching snippets of chatter from the servants: the meal is being served, the feast is gathered, the king is in the hall.
Scottish castles aren't much for decoration, not even the king's, but there's enough people coming and going for him to slip through, and he takes refuge against a chest in a corner, trying to catch his breath, trying to listen for Macbeth's voice. He thinks that voice will mean safety, will mean rescue.
He hears the murderer's rough voice first, and his heart near stops with terror. They've come after him, they'll find him, they'll kill him too. His fingers tremble as he wraps them around his dagger hilt, remembering his father's plea to avenge him. And he determines to take at least one man with him. He doesn't hear Macbeth's approach, or he may have leapt up with a wild determination to save at least Macbeth from the killers.
The first thing he hears from Macbeth is quick, anxious, so much so he's not quite sure it is Macbeth. "There's blood on thy face."
He's gone still, so still, stiller than a rabbit under the eye of a hound, he does not even blink, because the voice is right above him now, both of the voices...
"Well, better you without than he within. Is he dispatched then?"
"I cut his throat myself. But the son is fled."
The son is fled, yes, the son is fled to sit by and hear his father's best and dearest companion delight in his father's murder, and wish for the son's death. The son is fled to the shadows he thought would protect him, but he sits in the shadow of death.
He doesn't blink or twitch or even breathe for what seems a long time.
When he comes back to himself, the banquet is prepared, everyone is in the feast hall, where he can hear Macbeth's voice. The kindling of rage sparks in Fleance, and he draws his dagger, rising from his shadowed corner, suddenly uncaring for his own life, when none better than Judas stands in the other room. But he looks up, and... he would speak but he cannot, for he thinks he sees his father standing there, over by the stairs, shaking his head, and there's blood all down his shirt, but he's looking at his son, and Fleance can hear the words as if in distant echo—Fly, fly, fly!
Fleance is a dutiful son, he loves his father more than anyone else in the world, he will do what his father commands. So he sheathes the dagger. He slides back into the shadows, and fancies the shadow of Banquo follows him. (They are the lights relegated to the shadows, reduced to flickers.)
In the quiet stables (grooms away to their own supper) gathering the saddle, hands slipping over his father's handsome seat, seeing Banquo's sweet grey mare nicker at him, his hands begin to shake.
In the distance the hue and cry is raised, but he does not hear, for he is weeping suddenly, stumbling to Thistledown's side to cling to her neck, before he turns away and is violently sick.
No one hears him, no one finds him.
He takes Thistledown, rather than his own pony. Somehow he cannot bear to leaver her behind, as if she might be next for Macbeth to want dead. They ride out into the night, a chill rain blowing in from the east, and covering their passage. The boy has only his plaid, his dagger, his flint, a bit of bread and a small skin of wine pillaged from a groom's things, and heart breaking under the weight of betrayal and loss and loneliness.
He does not know where to go now. He knows he can never return. He knows he will survive.
