According to http://en.wiktionary.org/wiki/versipel versipel was coined by Nabokov from versipellous, which is formed from versi- ‘turning, changing’ (combinatory form of Latin versus ‘turn’) + ultimately Latin pellis ‘skin’. If Shade’s muse is driven by personal experience including that of losing own daughter, then versipel is indeed appropriate.

>When one is a mild and gentleman, fulfilled by the love of one woman, it is painful to be drawn from one’s life and one’s love by the demands of a muse that requires one to study once again the most painful moments through which he has lived. When your muse requires you to dissect the death of your daughter, this relentless self-examination is done under orders not of a dream weaver but of a demon.

- George