Well, the theory is that whoever holds the Spear of Longinus will have to decide the fate of the world for good or ill. Or at least that is one interpretation.
That could account for Harry's weeping on Christmas Eve. Triaging isn't fun at any time. Triaging is done in a disaster situation where there is an overwhelming number of patients. The doctor or ranking medical person in charge is forced to make decisions to save the most people.. The severely wounded or ill, possibly can be saved, but would take a lot of time and resources. In spite of those efforts they may die anyway, so they are kept as comfortable as possible but are set aside for later. Then we have those who are ill or wounded, but nothing life threatening, they also can wait. The idea is to concentrate on those who are badly injured or ill, but are very savable, thus saving the most lives. Harry might be put in the position where he has to set aside some of his friends who are in danger of dying because if he spends time and effort to save them, more will be killed. Thomas has already been set aside for later, Harry hasn't time to deal with him now.. The triage process has already begun.
