Wait how old are all of them??
I am pretty sure he was 16 at the start. I know, he even said it somewhere. He himself said, he was trying to get his heat (and Bella's) as late as it was possible, because it was better for their wellbeing as omegas, that's why he was selling himself to buy them drugs to suppres their heats. Which is still little bit too young tbh. (13 would be normal age to get your heat, I think. Just like women get their period around this age. When Daath was 16 and still did not have his heat, people around him said it was weird to still not have one at this age.)
Hope I got this right ^^











I totally want to see Tatsumi have his own story.