Feel like a bit of an outlier in that I don't have a very in-depth backstory for my PC's. My favorite has been RPing with my r!Durge Drow, Seid. The added Drow/Durge/intimidation dialogue is a lot of fun as someone who prefers to play evil (or at the very least unfriendly, with little care about any form of morality meter).
https://ibb.co/ZTvtKK9(Can't imbed on mobile apologies)
Her POV is arrogant, mainly focused on gaining power and making a legacy for herself in and beyond the Gate. She's not opposed to making allies with "good" people, as long as she thinks they're a stronger and more useful ally. Hence why you'll never catch her doing most of the stereotypical "murder hobo" options the game offers, despite her being pretty evil. She has a reputation to uphold, after all! Can't be *that* flippant and impulsive (just don't ask what happened to the bard).
Will be a bit spoilery. But it was fun to see the companions through the lens of an admittedly Neutral Evil character.
Lae'zel: Judged hard by her appearance. Quickly gained respect for her more forceful and forward nature, and her proclivity towards addressing problems with force. Later became a bit disenchanted by her weakness beneath the surface on behalf of her religious beliefs. Still a strong and capable ally. Held a lot of favor with my Drow.
Shadowheart: Was far too cagey and secretive to start. Absolutely did not trust her, and kept her around very little. Found her moodiness irritating. Fully expected to cut and run with her, until more of her story was unveiled. Seid was able to take her personal quest down a path she felt would afford her *a lot* of potential allies (killed the cult leader without killing the cult). Became more friendly to Shadowheart after that, and felt she was worth the trouble to maintain as a close ally, should she decide to step up and take control of the cult herself.
Karlach: Began hopeful in finding a devil as an ally. Especially one as strong as Karlach. Soon found her morality meter to be deeply vexing. My Drow felt that she would likely end up as a probable enemy, so kept her close for the time being, but knew she would ultimately be honoring Karlach's own request on her choice of fate (she felt this a mercy, and doing her a favor). So felt no need to be rid of her immediately when she could still be used for decent muscle.
Astarion: Was amused by him from the start. The only companion that seemed as eager as her to try and utilize the tadpoles for power. Felt thoroughly supported by him in her more wicked inclinations and goals. Despite a rocky start for trust, she was a bit charmed by his later willingness to confess his own vulnerability to her, and subsequent offering of the ultimate allyship proposal, and agreed to be his consort. Deeply amused that his revealed plans on how to take over the Gate together matched hers entirely.
Gale: Felt he was too emotional. Did not see much potential in him as an ally until he revealed his goal of piecing together the crown. Of course, she noted what a powerful ally he would be if he succeeded. His proclivity toward a more positive moral alignment kept her from choosing him as a partner, but she was ever so supportive in helping him achieve his goal of mending the crown out of the innocent goodness of her heart! (\s)
Jaheira: Recognized as a powerful potential ally. Also someone she did not want as an enemy. Decided to toe the line of 'good' in front of her in order to gain her Harpers, and the Guild as allies to keep in her back pocket. Probably the most interesting ally to RP with from a Neutral Evil perspective. Seid knows she is too smart to be a lemming. And is aware she has to toe a line with her, to gain what she offers.
Minsc: Mildly entertaining. Seemed to entertain her partner, so he was kept in camp. But likely the companion she would most easily underestimate. She felt he was useful fodder.
Wyll: Likely the only companion who could've given my Drow her own redemption arc. She found him deeply charming. A useful ally in battle. With a high potential for power over the Gate, which she could easily use to her advantage. Personally felt he made her weak, because she felt he could likely sway her away from seeking power. So ended up keeping interactions with him minimal once reaching Act II.
Halsin: Chose to do things he would find favorable in order to gain him as an ally. Found him friendly. But not suitable for her inner circle, so mostly kept her distance out of disinterest (despite me as the player liking him quite a bit).
Minthara: Another female Drow in the area Seid hoped to gain power and influence over. Eliminated immediately (fight on sight).
For this type of RP I really wished Nere was on the list of companions :'( but it's such a niche want, I'm aware!