Sherlock claims on more than one occasion to be a 'high-functioning sociopath'. However, according to Jim Moriarty, as well as Sherlock's own actions and displays of emotion and empathy, this may not be true. However, his unusual and somewhat aloof personality has led to many in the official police force distrusting and disliking him. He also often utilises his 'mind palace', a tool for remembering the smallest of details and organising his memories in a visual way. Sherlock is a thinker and an observer his notable ability to notice and draw deductions from seemingly trivial details is incredible and that is his main tool for solving crimes he investigates. Sherlock has a keen interest in unusual or bizarre crimes, without which he rapidly becomes bored, relying on nicotine to keep his brain active, although in the past he has dabbled in illegal drugs for entertainment, such as cocaine. ~ Sherlock thanking John for making him a better person

Today, you sit between the woman you have made your wife and the man you have saved, in short, the two people who love you most in all this world, and I know I speak for Mary as well when I say we will never let you down and we have a lifetime to prove that. John, you have endured war, and injury, and tragic loss. Mary, when I say you deserve this man, it is the highest compliment of which I am capable. But as I am apparently your best friend I can not congratulate you on your choice of companion. Redeemed only by the warmth and constancy of your friendship.

of the bravest and kindest and wisest human being I have ever had the good fortune of knowing. So if I didn't understand I was being asked to be best man, it is because I never expected to be anybody's best friend. I am dismissive of the virtuous, unaware of the beautiful and uncomprehending in the face of the happy. the most unpleasant, rude, ignorant, and all-round obnoxious arsehole that anyone could possibly have the misfortune to meet. The point I'm trying to make is that I am.

Sherlock holmes