I didn't really imagine you meant to sound callous - we all slip up and post things and later slap our heads - but what did strike me is that if writing about a character with a disability could become tedious, what you really mean is that it might become too much like hard work, because you will have to consider the disability every time he comes into focus. This isn't really true. Look at Heather Mills on that dancing show in the states - she's proving that a disability doesn't have to be disabilitating (is that a right word?). There was a case a few years back of a kid getting his disability living allowance taken off him because his new leg solved his mobility problems - it was a fair point; why should he have a blue badge if his disability doesn't effect him? It's not like the blue badge is compensation (Colin casually opens a fresh can of worms

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I wouldn't advise against your character's amputation just because it seems like too much to consider - the challenge might be to show him not as disabled because of his operation, but re-abled, if that makes sense. Having lost something, you suddenly realise all of the things you can't do. It makes many disabled people more determined to do those things. Slightly related, I had a friend who had to give up smoking for medical reasons. He told me in a pub one day how he had never realised how many different brands there were until he had to stop. "All I could think," he said, describing the tabacco counter, "was all of those brands I'd never even tried. And now I can't, I really want to."
It's a mad world.
Colin