Mothman originally came from Connecticut, according to Hollis Mason's autobiography. During his studies, he had left-wing friends.
A young prodigy, he soon made a fortune making patented inventions in the aviation industry. He was brave and thirsty for adventure and traveled around the world. Pictorial evidence on his office suggests he ventured as a hunter/explorer in the jungles and as a mountaineer.
He invented a glider suit, actually a set of wings of which he perfected after several near-fatal injuries. Before flying, he had to check the wind speed and air density, and his weight could vary by no more than three pounds, according to Hollis Mason. Because of the tremendous pressure put on him to stay in perfect condition, Byron developed an addiction to aspirin, liniment, morphine, and eventually a drinking problem. In 1939, a little after news of the Silhouette, there were reports of a man dressed like a moth who could glide through the air.During their first botched mission, Mothman had the role of aerial cover. Supposed to throw a smoke bomb inside the "saboteurs"'s warehouse, his bomb fell directly in a box of Chinese fireworks, causing havoc. During World War II he went with Mason to enlist, but they both were classed as 4F. He was a conscientious objector during the war and served as a medical aide.Lewis would often appear flying as a "surprise guest" during Dollar Bill's publicity "pep talks" to the children. By 1942, he became hard to get hold of, Mason took his place. Around 1946, after the end of the war, Lewis had bought an abandoned machine shop and used its enormous basement as a secret workplace; the building itself was boarded up so they used a manhole as its "entrance". Mason worked helped him with maintaining or improving his flying suit. There they learned of the death of Ursula Zandt and Gretchen. Lewis arranged for unmarked graves so that they wouldn't be defiled by haters.
Hollis and Byron had agreed to break into Gretchen's home and collect any evidence they would find surrounding the case Ursula was working on, but Byron was lost in alcohol and Hollis proceeded alone. That time he was taking hashish to remedy his back and knee ailments. The following days the two continued to work Ursula's case, patrolled and investigated for missing kids. He also attended Sally Jupiter's wedding to Larry Schexnayder.
When Japanese saboteurs planned to destroy the Statue of Liberty, Mothman was tasked to fly above and deliver a satchel with tracers, tear gas and Chinese fireworks. This diverted the guards, allowing the others to dock to Liberty Island and assault. Mothman landed on the Statue of Liberty's flame and saw the saboteurs completing the procedure. He hanged himself from the statue's crown and managed to shoot down the remaining henchman, but he was shot by the Japanese leader, and he fell to the ground. He entered a private clinic until healed.
During the '50s, the House of Un-American Activities Committee forced all active costumed vigilantes to reveal themselves to one of their representatives. Due to the left-wing friends that Mothman had cultivated while a student, his clearance was considerably more difficult than his companions. He was eventually cleared, but the investigations were both lengthy and ruthless. Mason speculates that the pressure of this meeting may have prompted his future drinking problem, but Laurence Schexnayder points out that the stem of his harder drinking was after the death of Dollar Bill.
Lewis was present at the ceremony in honor of Nite Owl where he was given the Key to the City. Having being told that Hooded Justice was behind the children disappearances and murders, they paid a visit to Nelson Gardner's mansion and then entered the Tower looking for H.J. Mothman saved Nite Owl's life pushing him when a crate fell on them, but he was hit, and then taken by H.J. who threatened them and asked them to leave. Nite Owl threw himself on him, killing him.
In 1960 Mothman and other former Minutemen attended a Red Cross charity event for the India famine. Hollis noted that he was always with a drinking glass, mumbling incoherently.
After a long bout of drinking, Mothman had a complete mental breakdown, and knowing what he would become, in 1962 he bought his friend Hollis a auto repair shop. That was his parting gift, as his condition worsened, and was admitted into the Overlook Asylum in Kennebunkport, Maine. Later that year, Mason had sent Lewis a draft of his book, Under the Hood. He paid him a visit there as Lewis was staring at the setting sun, but didn't receive an answer whether he did read it. Bryan also read the novel, Fogdancing, obsessively during his final years.
Later that year, his doctors gave him leave and his nurses brought him to Sally Jupiter's mansion for a brief reunion with former minutemen, Nelson Gardner and Hollis Mason. He seemed lost and was given a soda, but the glass fell from his hands. 13-year-old Laurie, Sally's daughter, asked her mother if that's what the future holds for the crimefighters. In 1983 Dan Dreiberg paid him a visit in his hospital on behalf of Hollis.
Between 1985 and 1992, he directed his fortune to aid the Byron befriended a newly committed patient, a young man named Reggie Long. Reggie was a survivor of the New York City Massacre, suffering severe mental trauma and psychic afterimages of the alien. Byron becomes notorious for his escapes from the asylum, donning a makeshift Mothman suit and flying off, inevitably being recaptured, but smuggling contraband inside the facility in the process. After his young friend suffers a violent encounter with an orderly, Byron teaches him how to fight, imparting the techniques and methods of each of the Minutemen to Reggie. He also repeatedly returned with family keepsakes and information pertaining to his father's final case: the vigilante known as Rorschach. The two became close friends over the years.
After Adrian Veidt was exposed as the perpetrator of the massacre, Reggie became determined to take his revenge. Byron escaped with him when Reggie set fire to the asylum, however, Byron began to hallucinate at the critical moment, and walked into the fire to his death. He left Reggie a final parting gift, giving him Rorschach's mask and the means to find Veidt. An obituary was published in the newspaper on November 23rd, 1992, with his history as a vigilante quietly omitted.
By 2019 Lewis' flight technology was successfully emulated by the pubic and evolved from the crude flight technology that he originally wore during his Minutemen days. It is notably used by photo journalists to capture pictures while flying with the help of wing-like suits. Tulsa detective Red Scare refers to the users of this technology as “moths" a reference to the original Minuteman.
Mothman wears an expressively gaudy costume themed like a moth. Although most are gray, he has a large letter "M" across his chest in bold red, as well as a red belt with a gold star and two antennas attached to his forehead. The most pronounced of his accessories are the two considerably large, bright yellow wings that supposedly flap when he is scared or possibly when he is nervous as well.
The character is portrayed quite differently between the original Watchmen and the prequel Before Watchmen series. In the few references and flashback scenes about him, he gives the impression of a bored or weak playboy who entered the superhero fad for his own reasons, before breaking. In the prequel, he is presented far more positively, and while his story is expanded upon, it is revealed he was a genius millionaire, and brave man, before eventually breaking.
There is also at least one apparently irreconcilable contradiction between the two media: In the original, Mothman's only speaking line in a flashback is about him being scared about the war and hoping the Minutemen keep out of it. This is contradicted by Mason's line in the prequel that the two enlisted for the war before eventually classed as 4F.
In the introduction montage of the Watchmen (movie) he is taken forcibly by nurses to an ambulance while still wearing his suit; in the Before Watchmen series he seems conscious of his health problems and he voluntarily enters the hospital, after his retirement.