The writer, Grant Morrison, explained why they picked such an obscure character: With The Human Flame, I wanted a Martian Manhunter villain, and I couldn't find a really good one.

Then, looking through the old Showcase Presents books, I discovered this stupid guy called Mike, who declared himself to be The Human Flame.

I needed a small-scale dumb guy, who could make very big waves and open the book with a shock moment and The Human Flame fit the bill.

[6] In the event, the Human Flame joins the Secret Society of Super Villains, becomes a cyborg after Professor Milo enhances him to save him from Heat Wave, and transforms into a fiery humanoid after infusing himself with radiation.

In Final Crisis, he is transformed into a cyborg with flamethrower implants, and later into a fiery humanoid who can increase his mass and density at will.