I think alastor has a tail, and hides it. something that reveals his emotions is dangerous, but most of all, is embarrassing! he cannot stay the mysterious and terrifying radio demon with such an obvious (and adorable) tell.
alastor thinks the tail alone is punishment for his sins. vox seems to disagree. vox has a weird fixation in it, somehow subverting every aspect of alastor that is terrifying, boundless, and conniving, in favor of seeing alastor as a cute (how disgusting to alastor this would be) thing.
of course vox recognizes alastors immense power, malignant behaviors, and ego. vox respects (and fears) him. however, vox also recognizes the good qualities about alastor, his chivalry, his enthusiasm, his ambition, his deeply buried sentimentality, and his unfortunate good looks. vox sees alastor as simultaneously a figure to be feared and a figure to admire or adore.
alastor does not understand how vox could see him as both and takes offense.
