This is a completely underrated scene.
For those who allege that Sherlock doesn’t care about his clients, look at that third gif. There’s real sadness and compassion there. During this scene, Henry is actively suicidal and keeps putting a gun in his mouth, but it’s Sherlock – not John, the soldier and doctor – who talks Henry down.
“Someone needed to keep you quiet; needed to keep you as a child to reassert the dream that you’d both clung on to, because you had started to remember…You couldn’t cope. You were just a child, so you rationalized it into something very different. But then you started to remember, so you had to be stopped; driven out of your mind so that no one would believe a word that you said.”
Does Sherlock only care about the mysteries? At this point in the episode, he already had the solution. He knew the workings behind H.O.U.N.D. and the poisonous gas. He could have left. But he wanted to make Henry understand, to alleviate some of the grief he’d carried since his father’s death. Sherlock even forces Henry to look at the dead dog to drive the point home. “You couldn’t cope. You were just a child."
It’s a remarkable display of empathy on Sherlock’s part.
Yes it is and I hope that over time we will see more of this! Sherlock Holmes has a very warm spot for the downtrodden. Abused women, the homeless, and especially children. In the original, his homeless network was made up of street urchins, basically homeless children. He recognised the value in the children that society had given up on and cast away. We don’t see this a lot in BBC Sherlock yet, because it is subtle. He is so guarded and so wounded. I notice that he is often self-absorbed in a very child-like way, almost as though some trauma arrested part of his emotional development. Here, we see his empathy for this adult who was very, very traumatized as a child. You could almost blink and miss it, but looking at his eyes his this third gif, it is clear that he has a really warmth and sadness for the child in Henry.