The Sorcerer's Guardian Chronicles of Tournai, #4

Savarin honed his Talent through years of study, and to achieve his goal of becoming the most powerful and accomplished sorcerer in Tournai, he made magic his life. Among the wealthy and noble circles he moves in, no one would suspect the handsome, refined, arrogant sorcerer's humble beginnings—which is how Savarin prefers it. He wants to be seen only as the man he's made himself. When Tournai's princes task Savarin with studying and strengthening the spells that protect the principality from magical attack, he is more than happy to do so. The spells are complex, centuries old, and exactly the type of puzzle Savarin is eager to solve. But to his annoyance, the princes insist Loriot accompany him on his journey.

Second son of a minor noble family, Loriot worked his way up the ranks of the royal guard to captain with single-minded determination and takes pride in his service to the crown. He must obey the prince's orders to protect Savarin, despite believing his skills would be best used elsewhere and his wariness of magic. UnTalented himself, Loriot has learned not only the benefits of magic but also its potential for harm—and how to counter it. He still believes it's best to avoid most magic entirely, which is difficult when he's tasked with playing guard to a powerful sorcerer.

Loriot and Savarin clash repeatedly during their journey, but the simmering tension between them doesn't only stem from their work, and passion develops into feelings neither expected. But Savarin must still secure Tournai's magical barrier, and his only solution will endanger both him and the royal family.