5/5 - Heir of Fire was my favorite book in this series by far. The writing and character development improved even more than Crown of Midnight, and new locations and characters made this a great addition to the Throne of Glass world. 
 Review hidden under spoiler tags!(view spoiler)[ 
 Celaena was sent on an assassination mission by the King of Adarlan, but found herself without motivation after the recent loss of her friend. She met a Fae named Rowan Whitethorn, who was a blood-sworn warrior to her aunt, the Fae Queen Maeve. Rowan took her to Maeve, who told her if she could prove herself able to handle her powers that Maeve would tell her what she knew of the wyrdkeys. As Celaena needed them to defeat the King of Adarlan, she agreed. 
 Celaena's powers and Fae abilities grew from Rowan's training as she began to heal from her past tragedies, becoming the warrior and Queen she was always meant to be. While Celaena learned about her own powers, Dorian and Chaol began the long fight against the King of Adarlan, even as the King built up an army of demons and witches to continue his reign of terror. 
 My Thoughts: 
 At the end of book five, I realized there are essentially three Celaena's - the character jumps are just that distinct. Book one was girly, wannabe assassin Celaena, Celaena of books two and three was a deadly killer coming to grips with her own magical powers and title, and Celaena of books four and five was a whole new person who owned her past as Aelin Galathynius. Book three Celaena dealt with major heartbreak and her struggles felt real to me, and I think this was my favorite "version" of her character. 
 Heir of Fire introduced a lot of new characters, the two main ones being Rowan and Manon Blackbeak. In this book I loved them (I had a couple complaints with how they were handled in book five, that'll come in a later review) and was happy they were around to give the magical world more depth. 
 Now for my favorite character in the entire series... 
 MANON. MANON BLACKBEAK. My favorite character by FAR was introduced and I love her so much. In Maas' world, there were Fae, humans, fairies, dark demons from other realms called the Valg...and Ironteeth witches. Beautiful, deadly, unfeeling, Ironteeth witches. They LITERALLY had iron teeth and nails inserted to better kill. They lived in three different clans: Blackbeak, Yellowlegs, and Bluebood. Manon was the heir of the Blackbeak clan, second only to her grandmother and the leader of her own coven of witches, who were simply referred to as The Thirteen due to their number. 
 Manon was introduced because the King of Adarlan made the Ironteeth witches an offer: fight for him on the backs of dragon-like beasts he would provide, called wyverns, and the witches could have their homeland back. The witches accepted, and the ensuing chapters from Manon's point of view showed their vicious fights to claim the wyverns they wanted and to establish rank in the King's army. The chapters where Manon unexpectedly claimed the wyvern Abraxos and worked to develop their connection made my heart die of all the feelings. Can you ship a witch and her wyvern? If so that's the only ship I care about anymore. 
 "Witches didn't need blood to survive, but humans didn't need wine, either." 
 AHHH. Manon is perfect. 
 I was happy to have Rowan around because it seemed like there was finally someone to tell Celaena the world wasn't all about her. He was tough and didn't give her any leeway just because she was pretty. He knew she was a killer and didn't care, because his hundreds of years of killing made him vastly more callous than she was. Celaena's broken heart from Crown of Midnight was slowly healed by Rowan's tough love and refusal to give in when she would lash out against him in anger. It was what her character needed and I was happy when their platonic relationship began to hint at more to come in the following books. 
 The training chapters between Rowan and Celaena were some of my favorites in all the books so far. Celaena, being Fae, had a Fae (similar to an Elf with heightened senses) form and an animal form (her human form). Rowan's animal form was a hawk and he could control the wind, both of which he used several times in tense life-or-death scenes. His teaching brought Celaena's Fae form out and she began to tap into her fire powers for the first time in a decade, and Maas developed that transition well. 
 Chaol and Dorian were in Heir of Fire but not as frequently. Dorian had moved on from any remaining feelings about Celaena and was questioning more and more of his father's actions. Chaol became tangled up with the rebels from Crown of Midnight, including Celaena's cousin Aedion who had previously believed Celaena dead. (I liked Aedion but he didn't really catch my attention until book four.) Chaol's slowness to accept Celaena's magic - and now Dorian's - was frustrating, but eventually he did start seeing the light and deciding where his loyalties belonged. (hide spoiler)] 
 Heir of Fire was 5 out of 5 for me. I liked every scene change, I loved the new characters, and it was just a perfect fantasy read that let me get lost in another world. I didn't forget the issues I had with the earlier books; if anything I was happy and impressed with Maas' improved writing.