Shar is also the goddess of loss; and often takes those in her 'embrace' who have lost everything and have nothing to turn to. Kind of like the patron saint of the depressed. Shar being Shar, that doesn't mean she really cares - but that is what is professed. Shadowheart, like Viconia came to Shar in that manner and sought solace with Her.
Now, Viconia lost everything because she wasn't quite as cruel as her Drow compatriots; and when romantically pursued by a good character - she actually turns neutral. Shadowheart, whilst certainly pious and not trusting in the slightest, she certainly *acts* liek a Sharran - Seems to have the most trouble with the choice of siding with Minthara and the goblins. I don't know, I don;t think her heart is *all* Shadow.
