It's like this, then. His world ends.
The people closest to him… they always leave. In some way, for some reason, he ends up one day traveling without them, as the lonely, ageless god. Because he goes on.
… But who will take it upon themselves to care for him after?
Even for a short time. A few more days spent in the TARDIS at best, returning from her brief trip to Amy in the past with the vortex manipulator, finding the console room empty. The gears and navigation to the spaceship set on an override to automatic piloting, and River quadruple checks trajectory calculations and stability readings and where they are currently located along some desolately abandoned star cluster universes from the Milky Way, before searching him out through the roundel-corridors. She's organic in her structure and in her make so it's possible for the TARDIS to pick out River's silent concern as she purposely wanders, or maybe the battered emotional state the Doctor refused himself to be in. For whatever reason, River finds him — huddled up in a shower, his hair a dark, stringy mop, pressing a hand over his reddened face and the other clawing the shower wall above him.
The soft, gaspy sobs racking his entire body are the worst. It's the moment he can't hold it in, where he fails again to prevent the inevitable.
Instead of pulling him out, out of his further grieving, River calmly joins him, blinking out the torrent of water drenching her finely stitched, taffeta-silk dress. Her curly bangs sticking flat to her temples and forehead. Soapy rivulets cascade down the Doctor's long, broad shoulders and his chest. She shushes him, hardly above a murmur, when he whimpers out her name, looking up with his wet, old eyes — this amaranthine, naked, child-like being — and gently combs short, red fingernails against his scalp. Feels his head sink to her collarbone.
Amy and Rory were two of the many companions, friends, precious and brilliant humans who were lost to the Doctor now.
But then again, it's her world, too — gone and snatched out of her hands as her mother's had gripped bravely onto her hand, River's lips touching Amy's sweaty, living skin.
There were no others she loved quite as much as her parents.
She'll go on. Because the Doctor continues to go on, after each time, after each companion.
Because she loves him.
And someone needs to act strong now.
I've already walked into the desert and self-destructed.
"Eleven having an anxiety cry in the shower."