Gerber appears himself by the first time in Man-Thing #3, where he helps Richard Rory
and Ruth Hart
who are stranded in the swamp where Man-Thing
lives by providing them gasoline. Albeit he doesn't name himself, the readers can recognize him by his shirt and the shape of his head. He then re-appears in the next issue, where Rory mistakes him for the murderous vigilante Foolkiller
(who at that point was hunting Rory since Ohio) and punches him.
Gerber's next appearance is in the last issue of Man-Thing series, where he reveals that all the Man-Thing's adventures written by him were in reality re-told facts to him by Dakihm the Enchanter
. He also states this will be the last time he will write them, as his involvement with Man-Thing ends putting himself in danger when the demon Thog
comes to get him after Gerber received one of the Nightmare Boxes. Joining forces with Man-Thing and Dakihm, they together stop Thog from destroying the reality, though the whole experience makes Gerber feel his work in the comics about Man-Thing is getting "too personal".
In the last page of the comic, he bids farewell to Man-Thing and Dakihm, and sends a message to Len Wein telling he, sadly, can't work in the series anymore.