The combination of “you USUALLY love to run your mouth” and “being a brat is kind of your thing, isn’t it?” really suggests a familiar intimacy between these two, only fueled by the way Alastor laughs afterward.
That laugh felt knowing, quieter, like he really was caught remembering a very, very specific private memory between them, a fond recollection before he quickly regains composure and pivots, as though Vox accidentally brushed against an old closeness that still exists underneath all the hostility.
What were you thinking about there, Alastor?