This character functions on a number of very important levels. Perhaps most straightforwardly, s/he is Clare's friend and confidante, mentor and inspiration. On another level, s/he is a metaphoric embodiment of the male/female energies embodied by Clare on the one hand and by Christopher on the other, a symbolic suggestion by the author that it is possible for those two energies to reconcile themselves, to come to a place of harmony and co-existence. It's important to note, however, that for the author such harmony can come into being only as the result of the amputation of at least a degree of maleness. In the same way as Harry amputates his testicles, the author seems to be suggesting that maleness needs to amputate its tendency towards violence in order to achieve unity with the female (in the same way as Harriet, once Harry's testicles are gone, is free to embrace her female nurturing side). It's important to note that Harry does not amputate his PENIS, making him not entirely female but something between, something both, something more balanced. In other words, the character of Harry/Harriet suggests that the female needs something of the male (power? assertiveness?), while the male needs something of the female (compassion? grace?).