Gabriel , also known as Loki falsely or The Trickster , was the fourth and youngest of the four archangels created by God. Despite the fact that he is the youngest of the archangels, he is still very powerful. Gabriel was very compassionate towards his family. Although he was the very first celestial to be seen on the show, he was the last archangel to be revealed. According to Gabriel, The Apocalypse was an issue he had to cope with on a daily basis.
When his older brothers, Michael and Lucifer , turned on each other and began fighting one another, he couldn't bear it, retreating to Earth as an escape. Gabriel loved both his father and brothers, but he was unable to choose sides between Michael and Lucifer, so he left Heaven and "skipped out" to Earth.
He rescued and befriended the Pagan god named Loki and soon went under "witness protection" and he began posing as the Norse trickster god himself. Gabriel described his experience at obtaining a vessel and taking on Loki's form as having a "face transplant. As Loki he killed people across the world that he deemed to be douchebags, though some he spared to spread the word, and eventually encountered Sam and Dean who foiled his plans on more than one occasion and discovered his true identity.
Once Gabriel was exposed, he eventually aided Sam and Dean in stopping the Apocalypse by telling them the secret of the Cage door, but along the way was "killed" by Lucifer. After the fall of the angels, Metatron created an illusion of Gabriel in an effort to deceive Castiel. The false Gabriel claimed that he had been in hiding, but disappeared once Castiel realized the trick.
Since then, both Lucifer and God have at separate times stated that they believed Gabriel to be dead. Years later, Gabriel was revealed to still be alive by Asmodeus , who was holding him prisoner and stealing his grace to give himself more power. It was revealed that Gabriel had once again managed to fake his death, but was ultimately captured and tortured by Asmodeus for years. After recovering and killing Asmodeus, Gabriel was informed of the transpiring events and chose to once more return to a life away from humans, angels, and demons.
