"TimeLord10, if you're going to look at me sideways, you could at least help while he's wailing for Mummy." "What's my job?" "Your mad grin suggests you would appreciate booby trap duty." "Aye, aye, sir!"
They actually got on relatively well in the books, though Holmes was somewhat disdainful of how lazy his brother could be. This extreme sibling rivalry, so far as I can see, is purely between the Beeb!Bros XD