Whitman Knapp first met Alpha Flight interning at the New Life Clinic, under the supervision of Lionel Jeffries. Lionel's brother, Madison was also known to be the smith for Alpha Flight. One of the members of Alpha Flight, Bochs , developed the bends on a mission and could not safely phase out of his robotic armor. He was brought to the New Life Clinic for treatment. Whitman had contact with the Canadian super team for some time after that as they often sought medical help from the clinic. He slowly, but surely, developed a close relationship with Purple Girl.
Lionel believed to have had his insane mentality cured, but ended up trying to kill all the members of Alpha Flight. He also revealed why he had chosen Knapp as an intern. Knapp had a latent power which Lionel activated. Lionel quickly changed his name to Omega after joining with Bochs and was defeated by Knapp and Alpha Flight. After the battle, Alpha Flight was impressed with Knapp's efforts and offered him membership in the group, Beta Flight, which he accepted. He served in Beta Flight until the Alpha Inquisition when the team disbanded. He chose to go back to being a doctor, having felt uncomfortable in the role of the hero.
Once back to his routine as a doctor, he began to think that he was a fictional character and even had 'conversations' with his creator. It was soon revealed that this was the work of the Dreamqueen, who was using members of Alpha and Beta Flight to gain a foothold on this world.
When Alpha Flight was re-formed, Whitman chose to remain as a doctor until much later, re-joining shortly before the Consortium attacked, possibly because Alpha Flight needed another opinion in diagnosing Diamond Lil's cancer. He eventually became the Beta Flight advisor and, during Beta Flight's first full mission, he was injected with poison by the Jackal. While his body recuperated on its own at Department H, the facility was attacked by the Hardliners. In order for him to live, his other selves, Apeman, Proto, and Highbrow gave up their lives. He soon discovered that he could change his physical form to those of his "other selves."
Manikin is able to summon three of his genetic relatives from various points of human evolution:
- Proto: A semi-sentient glob of primeval goo capable of floating and corroding substances through secretion of acid.
- Ape-Man: A pre-homo sapien hominid with enhanced strength and agility.
- Highbrow: An advanced human whose body was combined with technology who could float, had enhanced senses and the ability to teleport.
After Manikin was severely injured, his powers evolved so that he could change himself into his other forms. Knapp was also a skilled physician.