MASSIVE SPOILERS TO FOLLOW. READ AT YOUR OWN RISK. THANK YOU.
Ryan doesn't know what to make of it when the city appears through the portal. Part of him registers it as beautiful, or that it had been, once upon a time. Now it's all rubble and smoke and glass stabbing up into a burning sky. It's destruction on a level he has never seen before, not even on Orphan 55; that had been a clean sort of ruin, cleared away years since. This is fresh, new. Or maybe just absolute, leaving no-one to pick up the pieces.
He wonders if this city, awful as it is, really is the most important thing right now. According to Yaz, they're minutes away from an invasion of a Cyberman army, and God knows what's happening to her and Graham. And yet... He can't drag his eyes away from the portal, as though there's something in it rooting him to the spot.
Besides, there's something in the way the Doctor is staring at it, in her expression of shock and almost fear. It disturbs him, that expression. It's not that he's never seen the Doctor scared before, but this is new. He's never seen her like this.
And then.
"That's my home planet," she says, and oh. Oh.
All of a sudden, Ryan gets it. He gets why the Doctor has been so secretive with them of late. Why she refuses to talk about her home, why she always goes there without them. Why she's been so angry, on the verge of snapping any moment.
Her planet is in ruins, shattered, every inch of it razed to the ground. He remembers when they first met oh so long ago, right after Gran's funeral when they were stood on the street outside the house.
"Do you have a family?" Yaz had asked.
"No," she'd replied. "Lost them a long time ago."
Is this what she had meant? Not just lost, not just dead, but massacred? Because that's what this was, Ryan is sure of that, though he doesn't quite know how. It was a massacre, of any one and any thing living on that planet. Was this where she lost everything?
There's still something not quite right about it, but before he can even try to figure out what that is, the portal pulses and ripples, expelling a body from it, and... It's him. O, the Master, whatever his name is, and if Ryan weren't so shocked he'd launch himself at him, this man who almost killed them all too many times over.
Before now, Ryan might have thought that the Doctor, at least, would be pleased to see the Master again, for all she's been searching for him these past weeks. But her face has gone pale and she looks seconds away from falling onto the sand, as the Master tells her to be afraid. Ryan feels sick, and more confused than he's ever been in his life, and yet... Looking between the two of them and that ruined city, something falls into place.
Because the Doctor's planet has gone up in flames, and the Master is standing there, grinning, in the ashes, and rage is flickering in her eyes, and-
And, all of a sudden, Ryan gets it.