He is first seen in the campaign mission The Ark where he is shown destroying the Milita Fleet with his customized Northstar Titan.
He later seen during The Ark, where he nearly kills Jack Cooper by throwing him off the side of a Militia-hijacked IMC ship.
Viper returns to finish Cooper aboard the IMS Malta, but is shot down in the ensuing battle. Just when BT-7274 and Cooper think he's dead, he returns and tackles BT and plummets through the air with the Vanguard Titan in his grasp. They land aboard the hull of the IMS Draconis and engage in a frantic melee. He rips off BT's arm, but BT destroys his hatch. The exposed Viper is killed by Cooper with small arms fire.
There was originally a second Ronin Titan involved in this hectic exchange as seen in the E3 2016 Titanfall 2 Campaign trailer. Instead of BT tackling Viper after recovering from the fall, he would tackle a Ronin Titan, although the scene changes before anything else was revealed. What became of this Ronin is currently unknown. It is possible this Ronin was simply a stand-in for Viper, as to not spoil the boss fight in a trailer.
Viper has references and influences from Top Gun and Aliens. His line "Viper's got you in the pipe, 5x5" is similar to what the dropship pilot from Aliens says, as they are entering the atmosphere of the planet. His mention of 'Voodoo one' is a reference to Top Gun, as is his callsign. In Top Gun the character Viper is played by Tom Skerrit, who also appeared in Alien.