I feel like Merc did over-react, however I do feel like there is some misunderstandings about the character. 

Natus is suppose to be a flawed character, he is paranoid, socially inept, and probably a bit aggressive. However, he was built that way and was approved with that in mind. To give some insight into creating him, I had already joined 2/3 other RPs at this time (I am not sure if one I joined before or after this one) and I already had feel the aggressive bruiser archetype, the timid support archetype, and had a flat out crazy character. So I decided to create a character that I had never really played with before of a sneaky rogue character. And considering the premise of this RP was that the people just below the best of the school were sent out on a mission, I decided to make my character a young prodigy, someone who isn't a master of their field but shows great promise. 

If my character carelessly ran off to fight monsters, that would be one thing. But of all the things to accuse my character of, carelessness should not be one of them. He is hyper-vigilant to the point of paranoia. And while I probably should be more clear how far away from the group he is, I feel like you need a pretty ungenerous interpretation to presume he is far enough to be considered reckless. Even when he does warm up the group, he is going on the outer circle of the group as that is how he fights, usually stealth and trickery. 

I also feel like his point was misinterpreted after the first fight. Where he said he was going to obsurce the group's footpath, and then the commander chided him for acting alone and presumed that he was going to scout ahead. Footpaths typically are behind where you are going. I didn't bring it up as I didn't really feel like it was that important.s

I feel like I shouldn't have to justify a character that was approved. If you want to have his flaws come back on him, that is good story-telling. However, it feels like he is being criticized for doing reasonable things.