When Rye meets up with Dirk again, it is clear that he has met and developed some sort of relationship with Faene. It is then suggested that the two have thought of furthering their relationship to marriage.
At a Q&A Emily Rodda said that when writing his character, she chose the name "Dirk" because to her it sounded like someone who is the oldest brother in a family, someone who is good and strong, very brave, a leader and someone who is straightforward, and because "dirk" is the name of a type of weapon, specifically a long thrusting dagger.
Dirk was almost 20 when he left the city of Weld and was gone for a year and a day before Sholto, having turned 18 two weeks prior, went and was gone for a year and a day himself, before Rye, at the age of 16, left. This makes the relative ages of the brothers at the time 22 for Dirk, 19 for Sholto and 16 for Rye. This is a 3-year gap between the three brothers. This is not surprising, seeing as Emily Rodda is fascinated by classic fairytale tropes, such as the rule of three - three brothers, three choices, three Doors.