Michael

Michael is an antagonist of Gabriel's Descent. He is the leader of the heavenly host and believes that only by cleansing the world in fire can true righteousness be found.

Background
Michael is mentioned three times in the Book of Daniel, once as a "great prince who stands up for the children of your people". The idea that Michael was the advocate of the Jews became so prevalent that in spite of the rabbinical prohibition against appealing to angels as intermediaries between God and his people, Michael came to occupy a certain place in the Jewish liturgy.

In the beginning of the new age Michael led God's armies against Satan's forces during the war in heaven, at which time he was meant to defeat Satan. However, Satan was able to flee and the world fell into disorder, with no strong conclusion to the apocalypse.

From there he disappeared, although Gabriel often comments that she feels his presence still.

Appearance
Then I lifted up mine eyes, and looked, and behold a certain man clothed in linen, whose loins were girded with fine gold of Uphaz: His body also was like the beryl, and his face as the appearance of lightning, and his eyes as lamps of fire, and his arms and his feet like in colour to polished brass, and the voice of his words like the voice of a multitude. (Dan. 10:5,6)

Trivia

 * Archangel was the only mentioned Archangel in the bible.