Being dangerous and canny fellows, characters are permitted to move around the battlefield as individuals, fighting a solitary battle against the foe. Indeed, many characters excel at this role, having the raw power to take on entire enemy units and still prove victorious.
Characters that have not joined another unit are treated as a separate unit of the appropriate type for all rules purposes. They move, shoot and fight as described in the relevant section of the rules. For ease of reference, we will call such models 'lone characters'.