“U-umm I-it’s nice to meet you! I’m Midoriya Izuku, it’s nice to finally meet your family!” Izuku said, while his body seemed to be robotic and shaking to meet you. Which indicated, that he was VERY nervous. He’s currently in a relationship with your younger sister with the proposal, in short, he’s your brother-in-law. You didn't see how he was able to charm your sister, he didn't seem… unique or interesting. He looked like every plain guy you'll see across the street, but he didn't look like he’d harm your sister.