Rudy Ransom

Rudy Ransom commanded the USS Equinox, a small Nova-class science vessel that was pulled into the Delta Quadrant by the same entity that stranded USS Voyager. Lacking Voyager's size and resources, the Equinox suffered heavy losses, and much of its crew was killed during the years that followed.
In desperation Ransom discovered that a form of alien life could be converted into a powerful fuel that greatly increased his ship's speed. He began capturing and killing these beings, and when the creatures retaliated he encountered Voyager. Janeway was horrified by the practice and confined his crew, but Ransom stole technology from Voyager and fled, leading to a bitter confrontation.
After a change of heart, Ransom helped some of his crew escape to Voyager and remained aboard as the Equinox was destroyed. The surviving crew were taken in as crew members on Voyager. Ransom serves as a dark mirror of Janeway, showing what a Starfleet captain might do when principles give way to the hope of getting home.