[Had he known, he would have kicked himself for being so obvious. He looks at Jim, and then at Bones, then back to Jim, looking rather than seeing, hearing rather than listening. Spock withdraws his hand from Jim, squaring his shoulders, before he fixes Bones with an expression that is sadness, confusion, and shock all at once (He disobeys his Captain's orders, for one of the few times in his life). He doesn't know if he managed to wipe the tears from his face properly, but the blood is enough. He and Bones both know whose it is, who Spock failed to bring in because he came here instead.]

Doctor. [Distant, almost plaintive:] It would be more [logical but what was logic? It couldn't save your best (and perhaps only) friend from the inevitable] practical to explain how you were able to accomplish it. Given the existence of the temporal anomaly, through our actions we may have inadvertently created another parallel universe.

[He takes refuge in the concrete, clinging to it stubbornly. People did not come back from the dead - and he knew all the symptoms of radiation poisoning, he'd seen it all happen right in front of his eyes. He mentally starts reciting the list, and he has to know.]