Unfortunately, even Lona, as the Sea Witch, doesn't get any special treatment. There is nothing good in them... although if Lona gives up, this slavery will not be the worst ending.
I agree, this fate is not bad at all from the point of view that she gets food, medicine, protection and shelter in exchange for her to spread her legs and give life for the Fishkind people. Even if they are evil they can still use a jolly submissive co-operative Lona as an example for the others. After all, a sex slave that willingly rides is better than a slave that strugles and tries to escape. Eccma did a good job for the most part, i just wish that there was something more for those players who stay in the Fishkind camp for longer. At least new dialogue options and attitude towards her for being a good human.