Name
Frank, the taxi driver, is the second name check for Frank Miller (the other being Stan's surname). For me, Miller merited a second nod because even though (based on the full body of their respective works) I'd rate Alan Moore as a far better writer, it's Frank Miller's The Dark Knight Returns which I'd rank as the best graphic novel to date. Its story is far more “human” than Watchmen and, unlike the “worthy” graphic novels beloved of the Sunday broadsheets (e.g. Maus, Persepolis etc), it stakes its claim to greatness while staying firmly within the bounds of the most derided of all the comic book genres: super heroes. A number of factors came together to make me want to write Shades but The Dark Knight Returns was undoubtedly the single most influential.
Role within the story
Frank is a minor character. His most obvious role is as the uncle of Ryan, Craig and Rebecca Allen. It's clear that the three teenagers are close to their Uncle Frank who has filled their childhoods with tales of the heroic exploits of Doug, Boo and the other “older” heroes. Shades doesn't deal with the fate of the Allens' parents but the backstory I had in my head while writing the script was that they had died early and that Frank had therefore raised the children himself. If we ever finish Shades, that's a story I'd still like to write one day.
Originally, however, Frank's inclusion in the book had nothing to do with the Allens. He was just a solution to a very practical problem (see below!)
Taxi!
When I set about planning Shades, one of the first problems I had to think about was how Doug, in particular, might - in his heyday - have moved quickly from one side of London to the other without being seen. It's so much easier for super heroes in New York. Even if they can't fly, the buildings are all so tall that heroes can leap (or swing) from rooftop to rooftop and - if someone should happen to look up at the right moment - they're only likely to see a speck in the distance.
In London the buildings are lower. Someone leaping from one building to another could and would be very obvious. Move outside the Square Mile and the tallest building may well be nothing more than a three- or four-tier multi-storey car park. Eventually I decided to allocate Doug his own taxi (and driver!) London taxis are anonymous, everywhere, robust, incredibly stable and no-one bats an eye-lid when they cut up other traffic in order to get to their next fare quickly. I decided, therefore, that a taxi would not only be in keeping with the “local colour” I wanted for Shades but would also have been perfect for getting Doug across town - unnoticed and in a hurry!
