Christine Trelane was one of the humans who gained superpowers after Earth was bathed in radiation from a passing comet. Of these "Seedlings," she was notable for being a Seedling whose primary power was, ironically, the ability to activate other Seedlings.
She was recruited by Henry Bendix, the leader or "Weatherman" of Stormwatch, a United Nations posthuman super-team dedicated to protecting the world from evil superhumans. She served originally as the second in command, and her job was primarily to activate latent superhumans. However, after Bendix was ousted from Stormwatch, she took over as the new Weatherman and leader for a short time. Later Bendix returned, and she again served as first officer under him until Stormwatch's collapse years later.
Afterwards she grew disillusioned with her new desk job, and after she and her lover Battalion married, they quit the UN. They soon discovered a huge increase in their natural powers, after coming into contact with the man known as Jon Farmer, last survivor of The Throne.
Afterwards Battalion formed The Monarchy, and Synergy was among its members.
Synergy's primary power is to activate the powers of latent superhumans, but she can also enhance pre-existing powers (as seen when she increased Swift's abilities) or deactivate superhumans for short periods of time. Her energizing abilities can also be utilized as a power conduit in order to charge functioning devices as was attempted by Argos through a pandeimensional gateway with which he sought to bring his armies to earth.
They also have some offensive capacity as she could use them to bring down building complexs down in a massive blast of power. During her time within the Monarchy, Trelene's powers has changed, augmented to a degree where she could effect possibilities and probabilities to achieve a host of unexplained effects. Warping under her own power to get from place to place, even across other dimensions without need of a teleportation device.
She also gained a form of psychic imprint reading with which she could read the details of an object or persons history.
As Weatherman she received various cybernetic implants allowing her to link to the Stormwatch computer systems in their orbital base, but whether or not she retains them or any abilities from them is unknown.