I received this book as an E-ARC from the publishers through NetGalley - this does not affect my review in any way 
 Return Once More is definitely... unexpected. Its so rare to read books that are both considered to be science fiction and historical fiction! That's something I really enjoyed about the book - the characters were zipping through space and time with awesome technologies, all to understand and to be able to record the Earth's history (Known as Earth Before in the book). I really love sci fi, and I also have an appreciation for historical fiction (eg. in Stravaganza). Leigh managed to weave the two together very creatively. I really loved the science-y aspect of it! If I could choose where to go, as the characters can, it'd be in renaissance Florence *-* 
 The characters are nice. Kaia is incredibly curious about the past, but also about other people's business. She is also very determined to do what she thinks is right, despite the rules enforced on her by society. 
 Oz is surprisingly protective. Even though he is portrayed as somewhat a 'bad guy', I still liked his character and his hidden protectiveness. 
 Cesarion was almost too goody-good. I was sad that there wasn't a lot of character development from his part. 
 Kaia's friends were nice, but I'm a bit disappointed that their main character developments only happen towards the end of the book. It's only at the end that we see that Sarah is a tech genius, and that Annaleigh has a bit of a rebellious side. 
 Jonah (hehe same name as my bro) honestly sounded like a cool guy. I wish he could have come up more often in the book, though! 
 However, one thing that REALLY bothered me about this book - in which the relationship between Kaia, the protagonist, and her True, Cesarion, an Egyptian prince, was a central point - is that the romance between the two of them felt somewhat fake and enforced. I dunno, I just didn't like the to of them together. When the two of them first meet, when Cesarion is in mourning for his mother, he basically treats Kaia like one of his servants. Then, she goes right back to him (not explaining much to avoid spoilers). In this way, It seems like their relationship, even though strong in the book, seemed enforced. A lot of the time, Cesarion seemed confused as to why his feelings were strong, while Kaia knew that he was the one who's genes matched best with hers. I dunno, it didn't seem very genuine... 
 However, I do kinda like the idea introduced at the end of the book better, of Kaia and Oz being together. ^-^ 
 About the end of the book - it was sad. It wasn't even cliff-hanger-esque, and I feel like it was missing out some resolution. Again, not mentioning much, to avoid spoilers! But it's obvious that there's going to be a sequel. 
 The little mystery in the book was very interesting as well. I think that if that had been made the focal point of the book, rather than the romance between Kaia and Cesarion, the book would have had a different stance to it, and the story could have gone deeper. 
 The pacing and the writing in the book were both good, and kept me reading at an easy pace. Sometimes, their expressions were a bit strange though, I must say! 
 Overall, I enjoyed this book, even though it had a few things that bothered me. However, it is a good debut, and, hopefully, some of the loose ends presented in this first installment will be tied together in future books! :)