I was quite surprised by the looks of Zoe, and strangely less by those of Kian.
Probably more so because of the impact of the explosion at the end of Book 2.
When I saw the variations on the look of Zoe in the concept art released with Book 1, I did not realize that would change with the impact of the story.
I think that the evolution of the looks of Zoe @ Kian are great both to follow the timeline and the events.
But also to illustrate the impact of the experiences they go through.