Looking for sapphic and/or asexual book recommendations

Alright so I'm looking for some books to gift my friends who are both in their early 20s, ace and mostly into women. For both of them I'm looking for something with little to no spice, and either no romance or something sapphic that develops alongside the plot but isn't the main focus of the story. An asexual or bi/lesbian main character would be amazing!

The first one loves gore, intense stories, action, drama and tradgedy, thrillers, horror, crime of any kind, mystery and anything that's dark and twisted. Even better if the story really challenges your perception and messed with your head. A recent favourite of hers is the six of crows series, in which she really enjoyed the slow burn love story, as well as the themes, bloodshed and storytelling. I know she doesn't really like enemies to lovers, since she easily gets pissed off by people (she hated Kaz for a while after reading six of crows but eventually warmed up to him after reading it again a couple of times) so asshole main characters wouldn't be great for her. She also loves ambiguous endings that aren't quite "happy" in the traditional sense, but anything works!

Her girlfriend on the other hand is more into lighter, much less gory stuff. Ideally something that has adventure or mystery, or something a tad more cosy and sweet. Found family, slow burn or anything in that direction would probably be perfect for her! A happy or bittersweet ending is definitely prefered.

Thank you so much in advance!