@DatOneGuy King: I could pitch a fit about this but having the world's greatest assassin owe me favor should be worth it. Besides, I'd rather not get killed. It's not like I'm losing face over it anyway.
All these people posting theories about the mother being bad really need to go back and read the story. You guys do remember that the MC went on a mission to assassinate/fight the DEMON LORD whose troops were wrecking havoc on human kingdoms right? Maybe that kingdom was one of those that was destroyed during the course of the war.
Most likely that short noble from before. Someone might have reported to him about the girl and likely sent that assassin to take her back. Otherwise, it wouldn’t make sense how he just knew she was with him when they stormed the guild the next day.