Monica Rambeau has always been devoted to serving and protecting the public, both as herself and in her various costumed guises. Before she became one of the brightest stars in the age of marvels, Monica Rambeau was a dedicated lieutenant in the New Orleans harbor patrol, partnered with the daring John Audain. Monica’s life changed when old Rambeau family friend Professor Andre LeClare came to her for help; he had developed an other-dimensional energy-tapping device with financial support from South American dictator Ernesto Ramirez, who intended to use LeClare’s technology to create incredibly dangerous weapons. Ramirez had already begun adapting the technology for his own purposes with the aid of scientist Felipe Picaro, but LeClare and Rambeau joined forces to destroy Picaro’s prototype. In the process, Rambeau was bombarded by the device’s extra-dimensional energies and gained the power to convert her own body into energy and back again at will. LeClare urged her to use this power as a crimefighter, and she left the harbor patrol to become a full-time adventurer.
Dubbed Captain Marvel by the media, Rambeau sought out the Avengers for help in mastering her new powers and became a member-in-training of their group. Befriended and mentored by Avengers veterans Captain America and the Wasp, Monica soon graduated to full membership, serving a lengthy stint during which she became one of the team’s most valuable and respected members. One early complication was the memory of an earlier Captain Marvel, the legendary alien warrior Mar-Vell, a deceased honorary member of the Avengers. Rambeau felt awkward about inheriting his title after she learned of his existence, but she retained the name since the Avengers and others regarded her as a worthy heir to Mar-Vell’s heroic legacy. Another new Avengers recruit, Mar-Vell’s close friend Starfox (Eros), disapproved of Monica using the Captain Marvel name at first; but even he was soon impressed by Monica’s character and ability, giving her his blessing and saluting the new Captain Marvel.