Peter Capaldi is notably older than Matt Smith (25 years older in fact) and this will instantly transform how other characters, Clara included, will react to him. The Eleventh Doctor kind of slips into the situation, taking everyone by surprise and immediately latching on to the heart of the situation. I could see the Twelfth Doctor striding into the room announcing rather broadly I am the Doctor and I am here to save you all. I cant imagine there will be any bemusement or confusion by any character with this new Doctor, like there would have been with his three predecessors. This will be a Doctor that commands the situation, using a millennia of experience to solve the problem, like some educated professor who knows every text, every journal and knows exactly what study will help resolve the current situation. He has already played commanding figures before. A maverick head of news for The Hour, Randall Brown. Aggressive Malcolm Tucker (In The Loop, The Thick Of It) and The Angel Islington in Neverwhere, acharacter who watched over the inhabitants of London Below just as the Doctor watches over Earth in Doctor Who. It was also a series devised and scripted by current Doctor Who favourite writer Neil Gaiman surely he needs to come back for series eight to devise another fantastic adventure for Capaldis Doctor?