Spent a couple days reading through the document. I corrected some typos and made some suggestions and opinions. Obviously I am just one person with their opinion.
I will note that you used a lot of filler words and things that slowed down the pace when the scene should have been faster, mostly 'Then' or commas. I noted where I think they can be excised, but it's your call, others may disagree.
I will note I am not normally partial to these scenes, so I am not their audience, but I appreciate the work you did, and I read them. The comments I have are that you seem to use 'Mistress' exclusively during the scenes for Rixx. I am assuming this is intentional or somehow meant to drive into the reader that she's their Mistress. Maybe that works for subs or those kinds of readers, but during the other parts, you at least called her a 'little shortstack' or some other descriptions. If this is intentional, it's fine and it wasn't even that bad, but I could have liked a few other nouns or descriptions of Rixx interspersed through the scenes, even just 'gobliness' or 'green-skinned lover' or 'jade sorceress' in a few places.
We know she had family, and she mentions her Mom, who's presumably a goblin. We don't know anything about her father. Whether he's still around (or was), or what race he is. I doubt he's a goblin, since she has a massive cock she must have inherited from someone, so he's either a centaur, marefolk (unlikely) or minotaur (likely). Or maybe her sharp, pointy teeth and really long tongue came from him, but the cock definitely had to come from somewhere. Less important, you could add in later dialogues about her family now. Are they still desperate, likely moreso now. Why doesn't she have one or more of her brothers or sisters staying there, if not her whole family? Does she not trust the little thieves? Too much risk of her clients being seen and blackmailed? I just wonder is all. Maybe she is just sending them some cash and that's enough.
Other than that, I kind of wanted more description of Rixx. Everything we know we can basically find out in the first meeting or chat with her. She has tiny tits (which never come into play), a sizeable butt, and a two-foot cock and grapefruit-sized balls. (less important: sharp teeth, messy black hair, and an amber pendant). With the exception of noting some scars on her athletic body, there's little added in or commented on.
She never teases you with her teeth, you never get a description of her butthole, whether it's black or dark green or anything other than 'winking'. You never learn or experience anything about her dick and balls other than they're big. There's no talk of whether it's an equine cock or a human-like cock. There's no mention of a flared head or medial ring or whether it's veiny any real details. Whether she has pubes, their color or curls or whatever. There's no real sensation or experience of 'discovering' your lover (or Mistress) or learning anything. She basically says, "This is what I'm gonna do," and that happens. You never trail a fingertip over a scar, or feel her muscles, or describe her nipples. Not everything is needed, I just felt like I didn't learn or connect with her in a lot of ways that made it feel like the relationship had a meaning to it.
Only my opinions, other may agree or disagree.