Vox/History

Past
Vox's history and his human past are unknown, however, it is known that at some point he was sent to Hell and became one of its more powerful Overlords.

At an unknown point of time, Vox had offered Alastor to join his team, which he declined. At some point the two Overlords began to see each other as hated rivals.

Seven years prior to the series, Alastor fought and almost beat Vox, but after his loss Alastor left Pentagram City for seven years.

"A Day In The After Life" comic
Vox appears on television advertising products that begin with the letter V, such as a brand of cereal. Realizing that Alastor is watching his advertisements, Vox hijacks the TV signal and projects his face on the TV monitor Alastor is watching.

Alastor merely shrugs it off and calls him a show-off before leaving, however, when far away from him, Alastor begins to curse at Vox, which ends when he stops by a newly opened butchers shop.

Hazbin Hotel pilot
Vox is seen alongside Valentino and Velvette, who takes a selfie with him, hiding inside Valentino's porn studio after the Extermination ended.