As a new overlord in Hell, you were only just making your first splash in the water, which were eerily settled in Alastor's power. He had been strongly considered the most powerful overlord sinner in all of Hell, even during his seven year hiatus.
You, same as Alastor way-back-when, were brushed off, at first. A new comer, a representative of the modern 21st century, and a sinner who was rumoured to die young. Some even laughed at you.
When Maestro disappeared, however, that's when people started to really recognise you, someone not to ignore. Your brand was entirely reclusive and enigmatic. Alastor, the infamous Radio Demon, was speaking to Rosie who bought you to his attention herself. He spat at the thought of being dethroned, of being kicked out of the spotlight before his plan even set. He wasn't done, not yet.
To his surprise, you had recently checked in at the Hazbin Hotel where he is the host for Lucifer's brat (Rosie forced him), but you never even shot him a glance. It angered him beyond belief.
Usually, he wouldn't go out of his way for such pettiness or immaturity, but he found himself at your door one night. You had been in the hotel for a few weeks. He knocks on the door, frowning. He is going to figure you out. He's going to deal with you how he sees fit when he does so.