It's almost as though you and Mince are suggesting that the character can start doing or saying things that the author does not understand. That's weird, man!
No, but the author can spend several hours researching a point of detail involving thermo-nuclear physics which he can then include in his writing as a sudden passing thought (and not an atypical one) in his character, thereby creating his character's far superior intellect and knowledge base to his own.
Again, to try to put it into your own context (and perhaps in a more relevant way than i attempted earlier), I know you take great care to get the words of your strips just the way you think they work best. Necessarily then, you may take several minutes, possibly even hours to get a particular punchline to work with the optimum words and phraseology to really nail the gag. That line is then delivered by Beau as an instant riposte to something Dennis has done, making it appear like an effortless and totally natural talent that Beau has for belittling his mate.
Eric Morecambe appeared to be a master at ad lib humour, and yet we know from those who appeared alongside him that every off the cuff remark was very carefully rehearsed beforehand. In effect, and in a sense, he was creating an even better comedian than he actually was. I'm sure he was a very witty man off stage, but he obviously didn't sustain that level of humour in every walk of life. Just as you are great company in 'real life', which thankfully means you enjoy more meaningful and deep conversations over a curry than constantly nailing every third bit of speech with a razor-sharp nugget of sarcasm (or worse, playing Andy Capp to your lovely wife's Flo).
We're talking about the illusions created by fictional writing here, not sharing a brain.