A team which operates on the edges of the law in pursuing vigilante justice.
The Angels of Mercy is the team for the anti-heroes of the world. They avoid the public and news cycle spotlight when possible. Violence, law-breaking, and questionable morals are acceptable if not encouraged; justice is pursued by any means necessary. However, despite whatever ethical quandaries they may have, they still must be by most definitions heroes, and perform some action to benefit society, social justice, or the common good. They align themselves closer to neutral or chaotic good.
Angels of Mercy members are often more concerned with the plight of the individual than the law of the State. Where the justice of the State is blind, the Angels see things clearly. When the State is too hamstrung by corrupt politicos and bureaucrats to act the Angels are free to let slip the dogs of war.
They are the names of legends: Robin Hood, Sparticus, Joan of Arc, Minamoto-no-Yoshitsune. These legendary names and more are the inspiration of the Angels of Mercy. Those who raised weapons against tyranny and injustice for an oppressed people. The Angels take on the fight for the little guy - they defend the people who cannot defend themselves.