To me, this story occurs in another/parallel universe. The main protagonists are a species of cat/human that can change their appearance and their society's problems with a royal succession.
Further into the story an adventure into the past accidentally occurs during a major space battle. This side activity helps to reveal how the society came about, however, it creates a 'huge' conundrum for me.
The people from the future save the people of a city about to be attacked by neighbours, from a plague, and in doing so, they give an antidote to the plague that they create from their own blood. The DNA in the antidote then 'creates' the people that those from the future come from.
My question is that the above seems to be a 'closed loop', but where did the ORIGINAL DNA come from?
All that being said, I quite enjoyed the story and would have no problems letting my 16 yr old grand-daughter read it. Well done.