Amber
Amber is a highly regarded Master Sentinel, and as a result of her distinguished career, she was placed near the top of the list of mentors when she was promoted to Master. As a result, she had more or less her pick of the entire roster when she was selecting an apprentice. Her eventual selection was Violet, who tested out at or near the top of her bracket in every category.
Since then, Amber's life has been a busy tangle of taking care of her headstrong and energetic apprentice and performing her own duties as a Sentinel. In her younger days, Violet was quite a handful for Amber to manage, and there were frequent arguments between the two. Violet has settled down as she has grown up, however, allowing Amber more time to focus on her professional life recently.
Amber is a strong and skilled fighter, but her practical knowledge and ability to remain emotionally detatched have been her greatest assets during her career. The combination of these traits often makes her come across as cold and aloof, but she is genuinely concerned about helping people and making the world a better place.
Amber has led a very active life, and her words carry significant political weight as a result of her career. However, due to the somewhat confrontational nature of her work as a Sentinel, Amber has few close friends and a large number of enemies. Most of her influence is a result of her personal reputation and skill than any genuine friendship or loyalty that the public feels towards her.