Analyzing Mycroft in A Scandal in Belgravia:
I have spent way too much time looking at these screencaps, but I think Mark Gatiss is brilliant, so yeah.
1. Right after Mycroft knows his plans have failed. The shock is just written on his face. He can’t believe all the work has just come to nothing.
2. He realizes the terrorists found out through Irene and Sherlock, and he is upset with himself. He led Sherlock down this path.
3. Now, he is angry at Sherlock. How could his little brother do this? He trusted him, gave him what he needed: a distraction, cases. He is feeling betrayal.
4. This may be my favorite. Actually, it was this face that made me start looking at these moments. Mycroft is terrified. Just like that little break in Sherlock’s voice, when John is threatened, this is Mycroft showing he cares. In spite of everything, he loves his little brother. He doesn’t want to have to tell his bosses that Sherlock is the leak, but he is afraid he will have to, afraid Sherlock will be hurt in the process.
5. When all is said and done, Mycroft can’t do anything, and he is exhausted.
In like five seconds, Mycroft runs through the entire gambit of human emotions. I am obsessed. I could write sonnets about these five seconds.