6. Showing Off To Irene Instead Of Keeping A Cool Head
Sometimes, Sherlock's ego is his biggest weakness; it's been his downfall on many occasions, and his thirst for a mystery has nearly seen him killed quite a few times. In 'A Scandal in Belgravia', he just can't help showing off again. He hears out John's calculated plan to retrieve Irene's cameraphone, before producing it from his pocket just to get a smirk from Irene at John's expense and then he solves her mystery in under ten seconds without even considering why she'd want to know. And then, he's too busy flirting with her "I've never begged for mercy in my life" to realise what he's just done. He's the most intelligent detective in the country, and he's too busy trying to impress a girl to question her motives. No wonder Mycroft hit the roof. Sherlock very nearly blew it, and if it hadn't have been for a last-ditch, eleventh hour realisation that Irene Adler was in love with him, he could have royally ruined his big brother's career.
