Oh my God. That ending.
Parallel really surprised me with it's...thoroughness I guess. The worldbuilding/science of this was absolutely wonderful and well thought out. Miller obviously did her research, making this book so much more real, an added bonus with the contemporary feel this book had! And while it was confusing at times, it definitely helped explain a lot and the book so much more interesting, knowing why this or that was happening.
I really did love how we would switch between Parallel Abby and "Real" Abby throughout chapters, though I think it would've been just as amazing without the Parallel Abby parts! They were obviously completely different people, yet so similar. I was always guessing what Parallel Abby's actions were going to affect and my gut clenched every time she did something I knew would do something! It was really like reading two different scenarios, all stemming from one point--it was fascinating and completely well done.
The romance was definitely...interesting. While our love interests were decidedly different, they were also...similar...yeah, I don't make sense. But I definitely chose a team and did not like who Abby picked. Sure, he was sweet, but I liked the other guy so much better!
One of the other major romances was Caitlin (the BFF) and Tyler (the other BFF!). I felt like they were way too adorable with each other and honestly would love to get a story on their relationship!
And I loved our characters too--okay, maybe not Parallel Abby. She was so different from "Real" Abby , though it may just have been the situation. "Real" Abby was so headstrong and honest, and I loved how much she trusted Caitlin and how she wasn't dumb enough to figure it out on her own, like some YA characters. She knew she needed help, and she knew where to go--something that will always score brownie points.
Caitlin was an amazing BFF and absolutely lovable, in my opinion. Smart girls? Totally kickass. Like, seriously. She was kickass.
The plot was absolutely mindblowing. While it's a bit slow at first, it quickly speeds up and, strangely, made me tear up. I don't even know! There were so many things that made me cringe in expectation and honestly, scared me a bit! And the ending. Don't even get me started. That was...oh my GOD. I can't even. Just leave me alone in a corner to cry bittersweetly.
Dealing with the universal question of "What if" and touching on topics like soulmates and parallel worlds, Parallel is an absolute must read that I would love to shove in your face honest-to-God think everyone should read. Absolutely mind bending, wonderful, and beautiful, Parallel is going to twist your perspective on life and the choices you make everyday.