Gabriel has bluish-white hair and bright green eyes. His hair is short and mostly neat, and he wears a monocle on one eye. He wears a dark blue, nearly black coat and matching dress pants, with a white dress shirt and dark blue vest. Under his vest he wears a vivid green ascot. He looks like he is in his thirties, though he was born over a hundred years ago. More often than not, Gabe does not wear the coat, revealing off-white suspenders.
After fusing with a demon, Gabriel's Monocle appears to have a bulging green eye in it, with a catlike pupil. The metal ring of the Monocle is far more jagged, and his skin on his right arm and the right half of his chest are warped into a black and green, rough material rather than skin.
Born hundreds of years ago, Gabriel and his brother Luther were investigating cryptids in a since-forgotten ocean and Luther died underwater due to an unexplained accident. Gabriel went on to win awards and make various scientific discoveries, before using his knowledge to bring beings from Eden into our world, hoping to fill the godless void that was left due to Xeren becoming the Demon. He also made himself virtually immortal, though still not invincible. Gabriel had founded the billion dollar company Alchem Corp. He meets the original members of what would soon be known as Team Demon Light at the barn and drives them to a location.
At the end of Season One, Gabriel fuses himself with a demon using a device that took over a century to develop. This caused Gabriel to finally reveal the truth; he would do anything for knowledge.
Around this time, Gabriel repeatedly wrote in all of his notes the name YHVH, as well as a prophecy:
"When three become one and one becomes All, The tides will shift, and the world will fall."
Gabriel is a smart man, and is cold and calculating. Of course, these traits are not always bad. Gabriel is far above the level of the smartest people known.
Gabriel's ultimate pursuit is knowledge. He will do anything for knowledge. He will kill, torture, and maim just for a closer peek into the realm of Eden, and he does.