Character descriptions in the Marvelous Universe differ from those in the official comics.
The Kree were wishing to catalogue all unknown planets and sent their prized warrior Captain Mar-Vell to Earth. She was to be given a human identity in order to blend in and observe but a problem occurred during her assimilation. Captain Mar-Vell’s human cover, Carol Danvers, was completely unaware of her alien self. The decided to continue the project, using her as a sleeper agent hoping that this would let them see human life more honestly.
Carol lived her life as normal but with the Kree watching through her eyes. Occasionally, her instincts would kick in and she’d transform herself into Mar-Vell for protection, only to wake up again as Carol and have no idea of what happened.
Carol pursued a career in the United States Air Force, possibly driven by her military instincts. She was such a prodigy that she was contacted by SHIELD and offered the role of captaining their air squadron.
On witnessing the Avengers, the Kree decided Earth was too dangerous to remain in the Galaxy, and sent forth Ronan the Accuser to destroy the planet. On seeing Ronan, the terrors he’d unleashed in Mar-Vell’s past awakened the alien side in Carol. Finally, she realised who she was and she assumed the mantel of Captain Marvel. She renounced the Kree Empire and decided to become Earth’s Mightiest Hero, defending her found home from the evils of the galaxy.
She has the ability to absorb energy and then project it, however she usually keeps a certain amount of her absorbed energy within her so that she can use other powers including her trademark light blasts.