The whole situation is far from perfect.
It's snowing and it's cold and Theodore looks like he's about to kill someone. It's the first Christmas since the war's end, yet it feels even more miserable than the ones that preceded it. Theodore's house is dark and dead, dusty and dank, and Blaise is certain that it is colder in here than it is outside. No number of roaring fires could bring warmth to this place, he thinks.
It is Theodore's house now, not his father's. His father is in Azkaban, soulless and languishing in a cell far out in the middle of the North Sea. He was one of the final casualties of the war, and one of the many whose death was met with rejoicing rather than mourning.
Blaise's mother is dead. She was poisoned, though no one knows whether by her own hand or someone else's. Blaise can't bring himself to care; he is simply glad that she didn't take him with her.
Theodore is staring out at the snow in silence, looking for all the world like he is carved out of ice himself. Blaise cannot stand to be surrounded by all this death; his friend may as well be a living ghost in this graveyard of a mansion. There is nothing left for either of them in this world, and it's all through no fault of their own.
Suddenly Blaise knows that it can't go on like this; he has to get a reaction out of Theodore somehow: anything to prove to himself that his friend is still alive. So Blaise does the only thing he can think of – he kisses him. Theodore's lips are as icy as his eyes, cold, dead and unresponsive. That's when it hits Blaise that this is wrong. No matter what he wants, he can't afford to lose the only person he has left.
Blaise flushes scarlet and bites his lip. That may have been something he had wanted to do for a long time, but that doesn't change the fact that he shouldn't have done it. Theodore seems even more annoyed than he was before: but then he looks at Blaise and starts to laugh, a sound that is somehow even more disturbing than the silence was.
The whole situation is far from perfect – but then again it was never meant to be.