araminta-sparkles:

Ben Whishaw as Sherrinford Quinn Holmes (also known as “Q”,) Sherlock and Mycroft’s younger half-brother. 

• Sherrinford is the result of an affair Mr Holmes had when Sherlock and Mycroft were teenagers. He is eleven years younger than Sherlock, and eighteen years younger than Mycroft. Needless to say, they are very protective.
• Mycroft calls him by his first name, but Sherlock nearly always refers to him as Quinn.
• He has high functioning autism and often struggles in social situations. Like Sherlock, people often call him a freak. Despite this, Sherrinford is smart, witty and tougher than he looks.  
• He is able to seduce any man and is known for his numerous affairs with politicians and spies. One of his many nicknames is “Aphrodite.”
• He prefers the company of animals to people. This is especially annoying for Mycroft, who doesn’t appreciate cat and dog hair in his office. Sherlock, however, understands that animals help calm his brother’s anxiety and tells Mycroft to cut him some slack.
• During his work as Quartermaster with the British Secret Service, Sherrinford became smitten with intelligence officer, James Bond (also known as 007.) Needless to say, Mycroft wasn’t impressed. 
• Sherlock called Sherrinford before The Fall. After his brother’s “death,” Sherrinford became a recluse and struggled with alcoholism. 

Special thanks to the anon who requested this, I’d never have known about this fandom otherwise.