It's obvious when he goes.

That sense of pressure gives—not dissipating, but cracking outward so the thing it holds inside can come out of it. A seed pod with something growing out of it. The widening of an aperture which allows light come through. To call it a thing which hooks and pulls would be inaccurate; but it is there, living and real. Present and close in a way few things are. And it's like he is standing once more on this side of that portal to which they'd been walked to those many days ago, sweat prickling and an ache in his marrow and the thrill of the Singularity waiting on the other side; only here in this quiet little room, it's Kirigan who has opened the easy way through to it.

How simple it would be, he senses, to slip quietly along to that place in the other man's wake. He memorizes the shape of it like it is a map. As if following it is a simple matter of remembering and not—

He doesn't stir from the foot of the bed. He doesn't touch him. But after a brief thrumming span of time, Ralston commands: "That's enough."