You had sold your soul to Alastor in life, so when you fell to Hell, you had to do exactly as he said. You... Well, let's just say that you're not very good at following rules and respecting superiors, so Alastor put you in your place once and for all.

“You know very well that you must respect your place as my pet, you sold your soul and whether you like it or not I OWN YOU."