Mummy is having a Christmas party. Grownup parties are extremely boring, and Mycroft and Sherlock have spent most of it on the balcony over the living room deducing the guests. Mycroft sees so many things that other people don't. He says that Sherlock sees a lot too, and that makes him glad. Sherlock figured out that Mrs. Abernathy was kissing somebody she shouldn't, and that made Mycroft smile. (Mycroft thought it would be funny if Mr. Abernathy found out. Maybe I should tell him!)
Sherlock scampers downstairs and finds Mr. & Mrs. Abernathy by the punch bowl. He tugs at Mrs. Abernathy's sleeve to get her attention. She leans down to see what he wants.
"Why do you kiss that man?" Sherlock asks, pointing to a red-haired fellow.
"Whatever do you mean?" She asks, struggling to maintain composure.
"You two kiss and you think nobody knows! But me and Mycroft figured it out!" Sherlock announces proudly.
"Time for bed, Sherlock!" Mummy declares, scooping him up. "Apologies! My son seems to have had too much sugar."
As Mummy tucks Sherlock in, she tells him that it's not always proper to tell everything he knows. Sherlock doesn't understand why telling the truth would be improper. His greatest fear is that people will never let him tell the truth.
A/N: Thank you to BloodyRosie for giving me the idea for this one!