We could list a whole ten examples of Sherlock being an ass just to poor Molly Hooper, the pathologist who's a little bit in love with him. Some of the first scenes we see of Sherlock, he casually turns down a date with her and tells her that her mouth's too small; hardly the gentleman, is he? It gets worse for Molly. He tells her that the man she's just started dating is gay, and thinks that he's being kind by doing so, and come Christmas, he humiliates her in front of everyone, telling the room how transparent the effort she's making is, before realising how horrible he's being. He also highlights just how incompetent she is with relationships, pointing out that it's best if she stops dating for the sake of national security; he certainly knows how to make a lady feel good about herself. Eventually though, he comes to realise how important Molly is to him, and what a useful friend she can be. She comes to understand what he's like, and together, we all turn a corner. Molly helps Sherlock fake his death, and it's a relief that he's now kind to her. It's a lovely way to develop their friendship.
