Crystal Line by Anne McCaffrey

I've noticed a pattern in the Crystal singer series. Killa manages to get herself overwrought about something, storms off planet, and has some wild series of adventures as a result. I much prefer a character who grows and changes over time, and Killashandra seems emotionally frozen as a shrill and emotional wreck, at times. The other thing that seems to happen regularly when she departs in a rage is that she finds a man to attach herself to, and to sleep with. In this third volume of McCaffrey's series, she turns into a total slut. How disappointing.

Crystal Line starts off benignly enough, with Lars Dahl (from Killashandra) and Killa having partnered as crystal singers on Ballybran for a long time, usually quite successfully cutting enough crystal to get off planet and enjoy long sailing adventures together on a seemingly endless list of water worlds. Guild Master Lanzecki sends them off on a mission to investigate a new, possibly sentient, type of mineral or crystal that's been discovered on a barren world, and the first part of the novel is intriguing. I actually thought McCaffrey was going somewhere important with it, at first. This new discovery is totally ignored until very near the end of the book, when it performs a deus ex machina routine and cures Killa of her memory loss, so she and Lars can live happily ever after.

When they return, Lanzecki begins to take Lars under his wing, so to speak, and includes him in some of the day to day business of the Guild. Killa seems oblivious to this, except as it affects her time spent with Lars, and how it inconveniences her schedule. When Lanzecki, who has grown old in the Guild Master job, goes out into the Ranges and essentially commits "suicide by crystal thrall", Lars Dahl is elected as the new GM, and Killa refuses to accept both Lanzecki's death, and Lars' new position.

Lars Dahl has made a habit of recording his experiences dutifully, so he won't forget who he is, what he's done, or who he loves, when singing crystal messes with his memory. But Killashandra has been lazy about doing so, and there are some things that she decided long ago she'd rather forget (any failure on her part, for one thing, which reveals something not so flattering about Killa's character). Her memory is not so good at this point, and she becomes unable to distinguish between Lars and Lanzecki's tenure as Guild Master. There is a new techique for helping Singers to recover their memories, but Killashandra refuses to be treated, and cuts crystal by herself for the first time in decades, then runs away from the situation, ending up on a water world by herself.

Killashandra overstays her slutty welcome, and ends up with severe crystal withdrawal symptoms. She returns to Ballybran considerably weakened, and Lars takes her back out into the Ranges to cut crystal again, letting her symbiont heal. The Guild is in the middle of a crisis, with a decimated force of singers, mainly through attrition and low recruitment, and unfilled orders from the FSP worlds, that competitors are hoping to fill with their crystal substitutes. Together, they must double-handedly save the Guild from extinction, or perhaps merely irrelevance.
This was a series that began well, but faded out with a whimper.