The Dragonheart

The Dragonheart is a concept discussed throughout the book of the same name. It is the idea that people can take on the aspect of dragons most notable: their complete lack of fear. Being "Dragonhearted" is a compliment, though some snide folk would equate it to 'foolhardiness.'

By the end of the series, Jeriel takes on the name "The Dragonheart". This occurs sometime after he takes control of Realmhold, capitol of the Free Knights' kingdom.

Other Symbolism
The book begins and ends in a dragon's heart; Alcrisus initiated his foolish crusade in the heart of Tarascon, where the series also ends, stopping him.

Additionally, when one tames or bonds with a dragon, you are said to have the Dragon's heart, and Jeriel's goal is to tame all of the dragons and their riders accros Jurmangard, in order to stop Alcrisus.