Ethel's first appearance is in front of Hell's Gate in chapter 1. She's an infamous bandit and master trap maker. She's 29 years old.
Spoiler, click to view
Ethel "trained" Touka in the art of trap making and survival tactics following the end of the war between the Allard Kingdon and Farom when demons terrorized the Northern continent (3 1/2 years prior to the main story line). As a result, Touka refers to her as his teacher or master.Spoiler, click to view
Ethel aligns herself with the necromancers seemingly aiming for a similar goal, though she still helps Touka's group when possible.Spoiler, click to view
She seems to be attached to Touka and often wonders how he's doing when they're separated.