Books like the fiery heart

The Fiery Heart is the fourth book in Richelle Mead's Bloodlines series and was released on November 19, 2013. It is told from both Adrian's and Sydney's perspectives. As from the start of the series, Sydney Sage is an Alchemist who been assigned to protect the Moroi princess, Jillian Mastrano Dragomir, from the assassins who would like to overthrow Vasilisa (Lissa) Dragomir, the Queen of the Moroi, from her throne.

The novel begins where The Indigo Spell left off, when Alchemist Sydney Sage proclaimed her love to the Moroi Adrian Ivashkov. That starts their taboo relationship just as Sydney's younger sister Zoe is introduced as an Alchemist tasked to both watch over Sydney and learn from her. The Fiery Heart is told in alternating chapters, between Adrian's perspective and Sydney's. Sydney begins to accept her path in defying the Alchemists by being initiated in Jackie Terwilliger's coven of witches, which is named The Stelle. Sydney finds out from one of the witches that the oldest witch in their region, Inez, has had a history with personally fighting Strigoi. Inez claims it was because her blood tasted bad to them. Sydney has been having the same issue, and is immediately curious. She asks her mentor Jackie to take her to meet Inez. Things are further complicated when Sydney receives a call from her father, notifying her of his impending divorce and his expectation that Sydney will testify against her mother in order to win custody over the underage Zoe, and thus ensure that she will stay on the path to becoming an Alchemist.