do you actually use ashara, or just nod her off as being a pure light side companion?
personally, i don't want a pure dark-sided companion that enjoys malicious, useless slaughter.
i'd also like to point out that talos is more light-sided than ashara
but, anyway, i used ashara a lot on belsavis, corellia, and voss. i found that i gained affection with her if i did something rational; releasing cruel murderers to kill republic soldiers got me affection with her. another choice i made, which i guess is kind of spoilerish
does ashara want you to be nice if you can? sure. does she want you to be an absolute pushover? no, not at all. you'll gain affection with her for doing something evil that is rational. doing something cruel and pointless? yeah, you'll lose affection.
if you're asking for a romance option that takes pleasure in needless slaughter, well, you're asking bioware to write a bad companion. dark side jaesa is the only companion that comes to mind