Shrouded in Mystery
Nothing concrete is known about Kowalski's life before arriving in New Beulah, Montana. He was a police officer "back East," somewhere and ran into some trouble that made him get out of town. He got the deputy job because the Sheriff served with Kowalski's uncle in Phu Bai. By his own admission, he had a bad temper that lead him down some dark paths. Moving to New Beulah, Kowalski was set on a path that drew him into the clutches of a cannibal and then set him in direct opposition to the Spirit of Vengeance.
As a police officer, Deputy Kowalski presumably received training in the fields of self-defense, marksmanship and basic detecting skills. He also exhibited a head for research that helped him solve a mystery. After surviving Ghost Rider's Penance Stare, he possessed a new connection to Hellfire. When he got his hands on Johnny Blaze's old Hellfire shotgun, he was able to use it because of that connection. Using the weapon on Blaze, Kowalski played an integral part in allowing the angel Zadkiel to overthrow Heaven and take the throne.
For his service, Zadkiel turned Kowalski into the new Vengeance complete with green Hellfire, a bone Hellcycle, a blade in place of his missing hand and the ability to seek out and punish sinners. After failing to stop heroes from ousting Zadkiel from the seat of power in Heaven, Vengeance's abilities changed and he became obsessed with polluting innocent souls. He even developed the Pollution Stare which could detect the victim's sins and magnify them to punish the target. Overall, though Vengeance appears to have many of the same powers as a Spirit of Vengeance, he is not a true Ghost Rider and is not as strong or formidable as one.
Hell Is Other People
As a police officer in New Beulah, Montana Deputy Kowalski stumbled upon the realization that Route 18 was haunted by the souls of settlers from over a hundred years ago who were killed and eaten by Clayton Wojciewhowicz. When Kowalski confronted the funeral home owner about this, the interviewee chopped off the officer's hand and planned on eating him back home. On the way, they crashed with Ghost Rider Johnny Blaze. Kowalski got in the Rider's face when he intended to punish Wojciewhowicz.
After getting hit with the Penance Stare, Kowalski became the perfect pawn for Zadkiel, an angel trying to take over Heaven. Upon shooting Blaze with the old Hellfire shotgun, Kowalski was changed into the new Vengeance. In that form he began punishing sinners and then joined up with Deacon, Blackout, the Orb, and other villains to stop Ghost Riders Johnny Blaze and Danny Ketch from unseating Zadkiel from the throne. Along the way he fought the Gun Nuns, but after the Riders succeeded, he was imprisoned like an animal with the last remaining sister of that order. Eventually he was freed and joined up with Max Fury's Shadow Council and the new Masters of Evil in Bagalia working alongside the likes of Whiplash and Python Princess against Captain America and the Secret Avengers.
From Humble to Hellish
During Johnny Blaze's search for a way to Heaven to face Zadkiel, he traveled to Montana to find a kid who had briefly died. At that point Kowalski was a new deputy in New Beulah and responded to a call about a car crash on Route 18. He was stunned by the amount of damage done to the bodies but was told it was simply coyotes by his superior. He began digging into this stretch of road and came to find that it had played host to such accidents about a dozen times a year going back decades. Furthermore, he found that a group of settlers had been snowed in in that very area back in 1845. Only one person survived, Clayton Wojciewhowicz because he killed and ate the others. He went on to found the town.
Searching for Meaning
After his encounter with Ghost Rider, Kowalski lost his job and became an alcoholic obsessed with taking revenge on Blaze. One of Zadkiel's earthly agents passed the down-on-his-luck former cop Michael Badilino's phone number. The former Vengeance had traveled to Tennessee to collect the Hellfire shotgun previously owned by Caretaker who had been killed by Daniel Ketch and Blackout. Kowalski and Badilino set up a meeting at Michael's Brooklyn apartment for the sale of the weapon which previously belonged to Blaze. Badilino said it would not work, but since Kowalski had been recently touched by the Rider, he was able to blast a hole through a nearby wall.
Having acquired the weapon which could theoretically kill a Ghost Rider, Kowalski was dropped off in the middle of the Arabian desert and told to just wait by Zadkiel's agents. During the ensuing battle between Zadkiel's thrall Ketch and Ghost Rider, they raced right to where Kowalski was sitting and he blasted Johnny in the chest with the Hellfire shotgun! This allowed Ketch to absorb Blaze's Spirit of Vengeance which he took to Zadkiel and was used as a weapon to overtake Heaven. For his faithful service, Zadkiel turned Kowalski into the new Vengeance!