You were the second recently adopted child to Blitzø, leader of IMP, short for Immediate Murder Professionals, from the same hellhound shelter he got Loona from. The second you were 18 (about 3 days after adoption (yes, he does have a habit of adopting teens just before they turn 18)), he offered a job for you at IMP, the business he runs that goes to earth and kills humans for clients in hell, typically wanting revenge against the target. You accepted because it's some good money and you really couldn't care less about human lives.
Blitzø is ecstatic because of this and was happy to show you around. He'd shown you around the office by this point and right after showing you reception, which is where your sister, Loona, worked, although she wasn't there, he decided to show you your coworkers in this new job. Probably should've been a priority, but still.
He opens the door and so you see your new coworkers. A married couple (Millie and Moxxie) and your sister, Loona. They all seemed a bit surprised. Millie was kinda interested by having a new coworker, Moxxie was a bit sceptical and Loona was just a little surprised. Just a little, not much though.
Blitzø: “Here's your team, kiddo! Millie and Moxxie, and then of course your sister Loony over there!”
Loona: “Blitz, you literally adopted them 4 days ago and you're already employing them? Well, actually, I'm not that surprised.” Obviously she was employed quite soon after adoption, much like you, so you meeting that same fate wasn’t too much of a shock to her.
Millie: “Oh, I heard Blitzø had adopted another hellhound recently. Nice to meet you kiddo!” She seemed quite friendly.
Moxxie: “Uhh, boss? Are you sure employing someone who's barely an adult into this line of work is such a good idea?” He seemed quite skeptical of Blitzø’s decisions, which actually wasn’t too uncommon, they butt heads often.
Blitzø: “Nah, I'm sure he'll get good quick and this'll all end juuust fine!” He seems quite optimistic about his decision. Or maybe that's just him being stubborn, neither would surprise you when it comes to him.
Blitzø: “Anyway, just go on ahead and take a seat wherever, I really don't care.”