MST, yes you can control the NPC that you have been paired against... 

Also, this would be something of a trial for Canis to gauge the skill level of his recruits, besides showing them that they have a long way to go if they expect to survive in the arena. From the results of the fights, he will be able to tell who has the most potential in which style, as well as the spirit of the individual fighters when faced against bad odds.