Brainchild was one of Magneto's first Savage Land Mutates, and was involved in the Mutates' subsequent activities. Whenever the Mutates lacked a leader, Brainchild filled that role. Presumably, Brainchild remained with the Mutates in the Savage Land, leading them in the stead of Zaladane. He rarely attacked directly in combat, preferring to strike by surprise because of his relatively weak physical stature.
Several times, using the Savage Land Mutate, Brainchild tried to conquer the Savage Land. In one of these, using a device designed by Magneto, he tried to make Ka-zar kill Deadpool, but was eventually deceived. While trying to escape, Deadpool shot his pterodactylus, making him fall - apparently leading to him being eaten by dinosaurs. Later, however, he resurfaced and clashed with Finesse and X-23 while leading a horde of cybernetically enhanced dinosaurs.
Brainchild appears in the X-Men: The Animated Series episode "Reunion" parts I and II along with the other Savage Land Mutates including Vertigo, Sauron and Amphibius. Xavier briefly wonders if he is the "Master" the Mutates refer to and follow, but it is in fact Mister Sinister.