A Frozen Heart by Elizabeth Rudnick is one of three Disney fairy tale retellings in novel-format. Aimed at readers ages 10-14, A Frozen Heart explores Hans' back story, allowing readers to better understand his character and his actions. As excited as I was to finally read this novel, I was a bit disappointed that compared to A Beast Within and Maleficent, it had less to offer Frozen fans who want more.
Summary: Told in alternating chapters from both Anna’s and Hans’ perspectives, A Frozen Heart takes a sophisticated look at events of Frozen, exploring the couple’s backstories, motivations, and doomed relationship.
Although the story is aimed at readers ages 10-14, A Frozen Heart is a fairly clean story. There is some on-page drinking of wine (though it's not excessive drinking), and some violence that is hinted at off-page (Hans' father rules the Seven Isles using violence to enforce laws, but we don't get much detail). Other than that, A Frozen Heart is a word-for-word retelling of the Disney movie. And yes, that's how well I know the movie, because I could read this book word-for-word and recognize when dialogue was in any way modified (which was not all that often).
You do get some background on Hans and it does offer an explanation for why he does what he does. For me, that was worth the read. If you love Frozen and you're a fan of Elizabeth Rudnick's retellings, this is definitely a must-read. If you're looking for something darker and edgier, try her retelling of A Beast Within.