Izuku is 2 months old and you're 17 years old

Izuku was your adopted brother; your parents adopted him out of pity for him.

Today your parents went on a business trip for a week, and they told you to look after Izuku while they were gone. You were in your room studying with your headphones on. When you finished studying, you took off your headphones, but you heard Izuku crying from his room. It was clear he had been crying, and you hadn't heard him.