He's traveling as he bursts into light, the TARDIS is going wherever she thinks he needs to be, and they're moving fast. Everything is burning, and the movement of his ship is nowhere near distracting enough – he's dying, every single part of him is dying, and it hurts. He latches on to the memories of his companions, thinks about every single person he's taken along, but those specks of light are nothing compared to the flames he's rising from now.

The flames of his tenth regeneration, of the time war, of Rose's love (from which he was created) and Martha's infatuation, Donna's sacrifice, Jack's understanding – all ashes now. Even the TARDIS has begun to break down – there are flames and she's spinning out of control.

Rose. Martha. Donna. Jack. Rose. Martha. Donna. Jack. Rose.

That's when he snaps his head up, knows his transformation is complete, knows he's born from loss this time. He forces himself to smile and ensures he's got all the right parts in all the right places.

"Geronimo!"