Mercy was the chosen name of a telepath, one of the Kith who chose to join the MRA. Considered by Blood to be the soul of the group, Mercy was also the least powerful and could only mindspeak through physical contact.
Mercy joined the Kith in the 2110s, some time after the group's stint as mercenaries in Kamchatka. Together the Kith became the centre of a Mayan-prophecy religion/cult in Alaska. Run purely as a means to scam the gullible mundanes who believed their psychic powers were given to them by the ancestors.
By 2116 the scam had come to an end after science had verified the existence of telepaths and several trucks full of heavily armed men arrived at their compound. The Kith escaped the Temple through an underground tunnel, leaving all of their followers to be killed by a 60kg plastique bomb set by Monkey.
In 2117, while living in Nevada, Monkey brought home a very young but powerful telepath whom they come to call simply the Kid. Monkey had found him wandering the streets with a low powered telepathic Indian woman, who apparently glad to be unburdened let Monkey take the child from her. Blood, posing as the boy's aunt enrolled him in a local school under the assumed name James.
A short while later, Mercy was detected as a telepath in a mandatory screening at her workplace. Tired of the constant wandering and her relatively low abilities opts to co-operate with the law and volunteers to take the sleepers. The lethargic and soul destroying side effects are instant and devastating. An enraged Blood immediately takes off to remove "James" from school and move the family before anyone else is detected. Upon arriving at the school the children, including The Kid have already been screened though to her surprise, his test comes up negative.
In 2118, seeing that the Kith cannot run forever, Blood, Teal, Mercy and Smoke decide to join the MRA, secretly arriving at the home of Senator Lee Crawford they agree to serve in rounding up other teeps. Monkey objects and decides to leave the group, taking The Kid with him.