I definitely don't see him as DS either, but compared to my Light V Warrior.......yeah.
"My lord, weren't we meant to kill the (entirely innocent) Willsaams?"
"My lord, is it really wise to spare this Jedi (who has actively helped us)?"
"Your methods have been a bit...unorthodox to this point." (Quinn-speak for "my lord, wtf?")
(when we don't destroy Makeb) <"Malavai Quinn greatly disapproves">
Poor Yaellia's just sitting there with her head in her hands like "honey. plz. do I need to walk you through the Flowchart of Mercy again?" (She is a nerd. She made a flowchart. At least part of it is "IF we display reason and compassion towards our enemies, THEN maybe they will not escalate into another Great-Hyperspace-War-style genocide.")
I'm surprised no one else came up with the idea of suicide-by-Sith! The Quinncident with a romanced SW really, really strikes me as Quinn being caught between two options, both of which he thinks will lead to his death (either by failing Baras or betraying the Warrior) and picking the one where at least if he works her into a fine rage she'll probably make it quick. In my warrior's case, he saw her kill people for threatening her, so clearly she had the capacity, but she spent so much time being NICE he convinced himself she would be a Normal Sith if pushed hard enough. (He kissed her & was like "oh that was inappropriate" & she gave him time to think about it. She wanted to move slowly. She respected his boundaries. And this just confused him more, because he was never expecting mercy or forgiveness or love.)
Surprise, Captain! You thought it was A Mask, but it was me, True Love!