@daxrocket If I walk up to you in your house with an RPG-7 on my shoulder and say it's cool, I'm friendly, would
you believe me? Because that's basically the situation here: over the past year, her hometown's population has probably dropped by about 40%, with her regularly losing friends to monster attacks, and all of a sudden, this dude rolls up with monsters in tow claiming to be able to control them and that he's friendly. Oh, and he's human, who this chapter's confirmed regularly capture elves to be sold as sex slaves.
If I were in her shoes, my very first thought would be that if he's telling the truth about controlling those monsters, who's to say he hasn't been controlling them all? I mean, it's classic false-flag tactics to launch an attack on a target just so you can foil it and get in their good graces, so I'd even be wondering if maybe, just maybe, he was responsible for the dragon, as well. Hell, the fact that she trusted him so quickly after turning back the attack (that a paranoid person like myself would say came at a suspiciously good time for him to defeat) is more unbelievable than her initial reaction.