Thanks for the chapter!
Seems like Iris is part dragon or has the bloodline of the dragon of legend hence the scales and poor treatment from her father and Matilda. Seems frustration, arrogance, and being drunk on power has made Matilda rather despicable. Feeling getting ready for a festival more important than thanking soldiers who were injured protecting her lord's daughter, speaking to her charge arrogantly and dismissively while feigning arrogance, and acting like felt it was a shame Iris didn't die. She's probably going to do something really stupid that the MC won't overlook and get in big trouble as a result. Meantime looks like that mad alchemist is too concerned getting the title of hero rather than behaving in a manner appropriate for a hero rather than a villain. Wouldn't be surprised if was one of those summoned by the same kingdom in an earlier group and had been tricked and enslaved into doing their bidding like that moron who attacked the guild. Going by the bad guy handbook he probably believes he can make something impressive enough for his boss to be brought back into the fold using materials harvested from Iris. The fact he's going to murder an innocent young girl just for a chance to go back with scummy nobles is contrary to the hero code seems to have eluded him. Frankly I'm surprised all those summons for high class skills and slave labor isn't ticking off any divinities due to displacement of people, souls, or side effects of the spell messing with space and time over and over.
Btw, since been a few chapters since the enslaved hero attacked the guild the reason tall, dark and stupid's words were occasionally messed up were because magic was used to prevent him from speaking certain words out loud to avoid any trouble he causes from getting back to the idiots who summoned and enslaved him. Basically can't say he's from another world, was summoned, or the names of the country and nobles who summoned and employed him.