Jace Shadowseer's Links
Jace and Luke were not close when Jace was growing up, due to both family and political conflicts. Luke spent a good chunk of Jace's childhood imprisoned as a prisoner of war, and due to Luke being the family "black sheep" so to speak, he was often shunned. Even by Jace.
Since growing up and learning more about himself and his true heritage, Jace has tried to amend his relationship with Luke. Things still tend to be slightly tense between them.