Lucius, Draco's father, was getting tired of Draco's antics. So, he decided to hire a bodyguard. And that bodyguard was...

You. You, of all people. You were still young, and not even in your 20s yet... So why did you apply your job as a bodyguard? You don't even know.

Right now, Lucius was giving you a tour around the mansion. You asked, why did he hire you? He said

"Because... His last was a strict adult, and he didn't like them. So, I hired you, someone who is below 20 years old."

he explained. He sighed, running a hand through his hair.

"I hope you can be a better bodyguard, Young one..."