Deuterium Boy's costumes is one of the mysteries of the ages - how could a grown man allow himself to be seen in public in something like that? Anyway... The essential costume consists of an orange shirt with a red crest on the left breast with a "DB" monogram in black; red satiny boxer shorts over lime green tights; a similarly lime green cape ending just above the gluteus maximus; a yellow Useful Things belt, red satin boots and a simple green mask. All colours, of course, are of the brightest possible hue.
Hair: long, brown with a few blond highlights; and a neat goatee beard and moustache.
Eyes: brown
Height: 6' 2.5" (189 cm)
Weight: 175 lbs (80 kg)

Essentially similar to Hydrogen Guy's, only focusing on the hydrogen isotope deuterium (See Hydrogen Guy's profile for a complete description.) Deuterium Boy's powers are a bit weaker than Hydrogen Guy's, for two reasons - only about 0.1% of hydrogen is in fact deuterium; and the deuterium atom is twice as heavy as the normal hydrogen atom, so he requires more energy to accomplish the same results. This mass effect is also responsible for Deuterium Boy's maximum short-burst super-speed being less than Hydrogen Guy's by a factor of square root two. Deuterium Boy can also influence normal hydrogen atoms, but much more weakly than Hydrogen Guy.

However, Deuterium Boy has a few abilities that Hydrogen Guy does not. For example, his atomic senses of smell and taste can distinguish different isotopes of chemically identical species. (Quick physics note: "isotopes" of atoms have the same number of protons and electrons, but different numbers of neutrons. For instance, a deuterium nucleus has one proton and one neutron, while a hydrogen nucleus is just one proton. Since it's the electrons surrounding the nucleus that determines the chemistry of an atom, different isotopes of the same element behave identically except for their mass.)

DB has also developed the art of erecting a shield of metallic deuterium - this is an exotic material that only exists at the core of gas giant planets like Jupiter (and then only mixed with metallic hydrogen). This shield is both very light and very strong; but being utterly improbable scientifically speaking, it takes a lot of energy and he can only maintain it for short periods of time. Hydrogen Guy's tried this trick with metallic hydrogen, but has never been able to get the knack for it, so it remains DB's speciality.

On the non-super-powered side, Deuterium Boy is generally in better shape than Hydrogen Guy. Ignoring atomic super-speed, he can run faster. As far as simple strength goes, HG gets no super-powered edge, and Deuterium Boy wins out again.

Sabre; Deuterium Boy is an expert swordsman, out-matching even Hydrogen Guy without the Ruler of Elendil. Also the Deuterium-O-Rang, throwing weapons shaped like the letter D with a blade on one side, and a weighted handle on the other suitable for whacking bad guys (or hysterical partners) on the noggin.

Heavy water mocha latté. In other moods he's partial to Coke, and he was firmly hooked on Carffee during its short foray into the province.

Deuterium Boy is definitely the more stable of the Covalent Crusaders. As compared to his partner, he is less brilliant, but also less reckless, more responsible, and more aware that what they are doing is actually quite bizarre. Although more than willing to follow along on Hydrogen Guy's bizarre ride, he sometimes pauses and asks himself exactly what they're getting into.

Nonetheless, he has an easier time of absorbing himself into his superhero persona, and of balancing his real and surreal lives. Hydrogen Guy alternately revels in and struggles with the duality; while Deuterium Boy simply accepts the duality and proceeds calmly. (Which is the first step towards realising there is no duality...)

When he and Hydrogen Guy decided to become superheroes, they flipped a coin to see who would become "Guy" and who would be "Boy". Deuterium Boy lost - he is actually 3 months older than Hydrogen Guy. He sometimes feels that Hydrogen Guy is hogging the spotlight, and has to remind him that they are partners. When Hydrogen Guy was on sabbatical in Ottawa, he took Helium Girl on as his sidekick, and unsuccessfully tried to readjust his image as "the Deuterium Avenger".

Deuterium Boy is sought after by women and has a wide knowledge of obscure mythological figures to exclaim by. There is no doubt some connection there.

In addition to his elemental powers, Deuterium Boy has a few other unusual abilities. For some time - we're not quite sure when all this started - David has been able to travel and explore the strange dream-lands around our Earth. There he was tantalised by images of a beautiful raven-haired female. He sought her out, and finally found her working as a cocktail waitress for the abominable Alternative Gods in the tiki lounge of Club Kodor. Avalia, one of those rare souls who exist solely in the dream-lands, has been his incorporeal main squeeze since. Previously, he had a short kitchen-centred affair with a CIA agent named Desdemona in Welsh Guiana.

After being thrown into a dystopian future by a Mage called Z, and then transformed into an obese dwarf by Hydrogen Guy's incompetent wiring, Deuterium Boy temporarily started to believe that he was "Zoto the Potato Queen", receiving messages from the Cosmic Pie. Although he recovered from his temporal displacement, ectomorphic tendencies, and potato-centred mania, the Pastry is with him still. The Cosmic Pie will sometimes speak to him in times of crisis, and reassure him that everything will turn out for the best. He can use the encouragement, having been thrown down an elevator shaft, turned into a tree sloth, impaled by an explosive arrow, shot down a pipeline in a sensor bullet, and shot and battered more often than is worth mentioning, among other things.

While attending Simon Fraser University together, David Marcolin became a CSIS deep-cover agent, and was assigned to observe his friend Jim Evans as a "potential subversive". He resigned when they became Hydrogen Guy and Deuterium Boy and never mentioned it. However, Desdemona discovered his second secret identity and found that reports on Evans had been made in his name much more recently. Desdemona spilled the beans in front of Hydrogen Guy, and the issue made for some uncomfortable moments. Fortunately, HG and DB have buried the proverbial Ruler.

As David Marcolin, he shared Torrado's Zerfelda Prize in Physics with Jim Evans several years ago. Unfortunately he was unable to attend the ceremony, as he was finishing his dissertation at the time.