Fortune is the starting hero that remains most useful throughout the whole game. She's able to apply quick, precise, continuous damage, which enables her to neutralize many enemies with a ssteady stream of headshots. Her special can neutralize mobs, and her shield breaking ability pairs well with overheated pistols to take down boss enemies. Later in the game, her agility and master programming ability make her MVP on many mini objectives, particularly the Dark Matter Fracking Drills (though higher difficulties will remove the autohack option). Her communal upgrade of extra cash is also handy for getting your favorite ARK upgrades as early as you can.
Fortune is a playable character from the very first mission onward.