A/N: This...is pretty much guaranteed not to be canon, but I thought that it was interesting, lol. And I didn't actually read chapter 140 before I wrote this, so...
To say that the Undertaker was not pleased would be like saying that a hurricane was just a bit windy. It would be like saying that the Siberian tundra, with its layers of ice and snow and permafrost was just a bit chilly. And it would not be far off to describe his will as something like a force of nature as well. But even he was not omnipotent, and it had never been more clear to anyone than himself that he was not omniscient. But he was old, and used to being able to direct things his way, thus making recent events, already unpleasant, all the more unpalatable.
As flames licked at the walls around him, the Undertaker gently lifted the small body Ciel Phantomhive off of the altar where he'd been left, and cursed his own impotence. This was what he was reduced to, arriving too late to prevent further tragedy and stealing away a body better left to burn with its secrets. However, with demons afoot, and the house of Phantomhive teetering on a precipice, it seemed as though he had little choice.
It was a bitter choice, however. That became ever more apparent as he watched the newest Earl Phantomhive trip and snap at shadows trying to taunt out his enemies. One living child, and one dead one, and one would come to ruin at his hand if he acted, and the other if he did not. The Undertaker knew when he stood in that desecrated church what the child meant to do: to sacrifice himself utterly for the sake of vengeance, to destroy himself in the process. And the Undertaker couldn't just allow that. The demon was a problem, of course, but honestly the easier of the two; the former shinigami had no lack of faith in his own skill. No…the real problem was the child himself, uncaring for his own well being. The boy was using himself as bait. For the people that had managed to kill his father.
The Undertaker had one living child and one dead one…and he knew which one he was willing to sacrifice (it wasn't the child who was running around with the demon). Well. If the "Earl of Phantomhive" was the bait that would draw out their enemies…then the Undertaker would provide. No matter to what twisted depths he had to go, he would not fail again.
The dead cannot come back to life. Not complete, not real, not whole (no matter how he wished). And a doll is only a doll, is nothing compared to a person. Bizarre though his methods may be, and convoluted and horrific, he would protect the last living Phantomhive even if it required putting a stand-in in his place. He would not let that child fall.
"Pantomime: significant gesture without speech"