Whoa, this book loves to twist your mind. I’m not even sure how to review it without giving anything way because it’s incredibly layered and one of the main themes of this book is how everything is interconnected. We can’t truly differentiate between “small” decisions and “big” decisions because there is no such thing as a small decision. I really appreciated the way this book assumed intelligence on the part of the readers to follow the logic behind how Abby’s choices affected her two parallel selves.I think it’s safe to say this book is science fiction, with the parallel universes and all, but at heart I think it feel a lot more contemporary than I expected at first. Abby has to deal with going back and forth between the parallel version of events, but a lot of the conflict centers around family, friends, and boys. Speaking of, I really liked the way Abby’s friends and family members were portrayed as fleshed-out characters of their own. Caitlin is a supportive best friend, though I will say I thought her character was just a tad overdone. She’s incredibly smart(a scientific genius, really), looks great all the time, and has one academic flaw(dyslexia). Caitlin’s character felt a little to characterization-by-the-book for me, but Caitlin and Abby do have a really solid friendship that I enjoyed reading. Abby’s family isn’t a huge part of the book, considering for quite a bit of it she’s away at college, but during the events when Abby was in high school, there were no cases of the mysterious absent parents here.I will warn that there is a love triangle in this book. I didn’t mind the triangle at all though because it’s not really a triangle. . . more of a parallelogram? Because Abby has a love interest, and her parallel has a love interest, so they interact with each other(I’m not good at explaining this, but the book does a slightly better job, though you definitely have to stop and think about it). So even if it’s not exactly a love triangle, there are two love interests. They were both all right, but I really liked one(Josh), while finding Michael just kind of . . . meh. He wasn’t a bad character, but he did seem kind of bland.Even though Parallel was a page-turner for me, I will say this is a book I would only recommend on certain conditions. I really liked it, but I think it’s going to be a polarizing book–I don’t see many people being on the middle ground with this one. So, a few warnings of things that came up in the book that I think might be off-putting to some people: there’s talk of soul-mates(it wasn’t instalove or sickening like I sometimes find this concept, but I know some readers really don’t like those words), all the kids are really, really smart(a little unbelievably so), and this book does sort of mess with string theory, which doesn’t bother me because I know nothing about string theory, but it might ruin the experience for you if you actually know your physics.The Ending to this book was definitely a “whoa, what just happened?” moment in a good way. It was so twisty and awesome–it might be one of my favorite ending I’ve read in any book this year. It’s perfect. I liked the book a lot going into the ending, but the last few paragraphs erased any remaining doubts in my mind that this was an awesome book.Final Impression: Parallel was not at all what I was expecting it to be, but I really enjoyed it. It was less sci-fi than I thought it would be, but I actually enjoyed the way Abby interacted with her friends, family, and the male characters. It was a page-turner and I never wanted to putting down. Also: BEST.ENDING.EVER(OK, maybe not ever, but I really like it). Really 4.5 stars, but 4 stars for categorization’s sake.Disclaimer: I received a copy of this book via Goodreads First Reads giveaway.Reviews originally posted on my blog at Book.Blog.Bake.