After reading the second book, I just can't. I've lost all respect for it. The second star is there because I know it deserves more, not because I like it at all any longer.
I won't talk about the second book here. I'll say that I liked Intertwined. The characters were mostly okay, if not great, and I loved the premise of the spirits in Aden's head. It was something I'd never heard of before, and I enjoyed their banter and their consistent presence throughout the book. I liked that there were monsters in the book, albeit not as many as there should have been, and those there were should have gotten more attention. The writing wasn't great, but it was okay. The first scene of the book, in the graveyard, is still one of my favorite opening scenes.
I feel so sad for this book. I hate myself for giving it a measly 2 stars. If I was recommending Intertwined, I would say, read the first one ONLY. And don't put it high on your priority list, either--it was good, definitely worth reading, but it didn't blow me away.