Ashcroft was just another A.I.M. Agent serving under Sub-Commander Blake, on the mission to retrieve a biological weapon - Headpool - from the Savage Lands; which Blake had hired Deadpool for. While under Blake's command, Ashcroft tried his best to keep him from doing more harm then good, but he failed with each attempt.
When Deadpool returned with the Headpool and then inexplicably stole him, Ashcroft loyally followed Blake to hunt him down and take it back. While on the hunt, Blake led his team through a portal that had been opened -- by the Sorcerer Supreme -- into Headpool's universe. After entering the portal, the team remaining of A.I.M. agents were attacked by hero zombies; leaving Ashcroft and Blake as the only survivors.
Still searching for Headpool, they managed to "meetup" with Deadpool and convinced him to take them along in his helicopter. After making a pit stop, Ashcroft and Blake stole Headpool after knocking out Bob, tricking Deadpool and Dr. Swanson into attacking a non-existent party of zombies and then stealing the helicopter.
Unfortunately, Headpool bit Blake's finger off and made them return for the cure. After some begging, Deadpool gave the cure to Blake and they continued their journey home. Shortly after lifting into the air, Blake began to act strangely. When it was clear he hadn't been cured, Deadpool admitted to lying; to see how long it took to become a zombie. Blake - now a zombie - cursed Deadpool and threatened to eat him. Having had enough, Ashcroft pushed Blake from the helicopter to his death.
While momentarily mourning the Sub-Commander, Deadpool asked him why they should keep him on board, to which he responded, "Zombie Fodder?" Ashcroft accompanied them into the swamp with the portal home. On the way, they were attacked by Zombies and in the end Ashcroft truly became Zombie Fodder.