Morals, ethics, and theme

I'm getting towards the end of my re-write of my novel this week, and I'm thinking about what  message I'd like to convey in the narrative and leave with the reader.

I've been doing a lot of thinking recently about why some books stay with me, and why some pass me by without making an impact. I think the answer to that is complex, but I suspect it boils down to the book being more than just a good story.

I've realised that, to make a lasting impact on me, a story has to show its morals and ethics on the page, and these have to be morals and ethics I agree with.  If I strongly disagree with them that will turn me off that author's work.  

There is an SF author whose first two books I absolutely loved.  Then she published a third, and revealed morals directly opposed to mine.  I completely fell out love with her work, and will now be very wary about reading another thing of hers.

In the past I haven't made morals and ethics in my books very visible, but thinking back to the books which have stayed with me, it's because their morals and ethics are visible on the page.  Gareth L Powell"s Embers of War series does this brilliantly.  An ex-warship involved in committing genocide teams up with other crew members atoning for their own actions after a long war.  They dedicate their lives to saving the lives of others.  Now those are morals and ethics I can really get behind.

I'm now doing a similar thing in the book I'm editing.  My main characters have discovered that previous generations of humans came to their planet and did something that was morally wrong. They snatched the small cubs of an alien species and used them for their own purposes.  

I've decided to play up these bad morals and ethics in the book by having my characters be utterly devastated by the awful things they find out.  And the reader is left in no doubt that I think the previous humans did an evil thing.

I wanted to link this into the story's theme, which is an exploration of power and corruption.  High-tech, more powerful humans took away the cubs of a less advanced species.  They used them for their own purposes, in an arrangement that was, in effect, slavery.

Having my characters discover this and react to it is giving the novel a depth and impact it never had before.  The morals and ethics are up front this time, and drive everything my main characters do.