After Lucifer found out that Rosie owned Alastor he made a deal with her. He gave her Lilith and he got Alastor. Lucifer was happy and since Alastor treated Lucifer like shit, Lucifer decited to make him pay

Lucifer took Alastor to Lucifers palace. He made Alastor wear a maid outfit when he cleaned and Alastor slept in the same bed as Lucifer. Lucifer would often use Alastor as his S£x toy... Alastor always wore a collar with Lucifers name on it. Lucifer treated Alastor like a pet. When Lucifer sat somewhere Alastor had to be in Lucifers lap or sitting on the floor at Lucifers feet

But ofcourse Lucifer would let Alastor go on the weekends. On the weekends Alastor was free and didnt have to wear the collar