"Kindhearted one, your heart aches with worry for your people, does it not? It is true that not all will be safe, even in a world under His rule. Those who do not repent breaking His teachings will suffer His judgement. But, man has continuously chosen to walk a fool’s path. When the unjust kill the just, and the righteous shed tears, can all truly be forgiven?"
—Remiel, Shin Megami Tensei: Devil Survivor
Remiel, also known as Ramiel is a demon in the series.
Remiel, whose name means "Mercy of God" or "Compassion of God", is an Archangel of whirlwinds, thunder, hope, and earthquakes who has various apocalyptic functions in Christian and Islamic lore. He is charged with leading souls to judgment and to spread the instructions of God to man. He knows which souls will be saved and which will be destroyed and will guide the souls that will be saved.
The words he conveys appear as visions to people and is often called the angel of "true visions." When Remiel is near them, they are like to hear the rumble of distant thunder. He is a very powerful angel, so it is unlikely that someone call upon him unless they are serious about making big changes in their life. He is said to have been the archangel responsible for the destruction of the armies of Sennacherib.
Ramiel, whose name means "Thunder of God", is believed to be a fallen Watcher in the book of Enoch. Ramel is the 6th of 20 leaders of the 200 angels that are turned into Fallen Angels due to mating with human women and the teaching them forbidden knowledge.
Before his fall, Ramiel was tasked into watching over the humans alongside his brethren, and provide thunderous sounds that accompany the lighting being conjured by the archangel Barachiel. It is said that Ramiel was Barachiel's lieutenant before his fall, with two embodying the forces of thunder and lightning.
Remiel is fought in Amnesia's Ahlabot on the Neutral, Light-Law, and Dark-Chaos routes.
Devil Children Fire/Ice Book
Remiel is one of the angel servants of Lord Enoch. He is summoned by Lena to confront Jin when he gets in her way. Upon his defeat he will flee in order to fight Jin another day. After the fake Enoch's death he will try to search for Lena in Niflheim, where he can stumble across Jin and ask to join him, as he learned that the Enoch he was serving was in fact a fake after his defeat and wishes to save Lena.
Remiel appears as the entity possessing Amane, working under Metatron's orders. During the 5th and 6th day, he speaks to the protagonist (through Amane) proposing that he becomes a new Messiah as the King of Bel, and is revealed to be suppressing the demon Jezebel, who is sleeping within Amane's body. On Day 7 of Amane or Gin's routes, Remiel will enable the party access to Amane's soul in order to defeat and absorb Jezebel. Upon eliminating her, Remiel leaves Amane's body, entrusting her with guiding the party through the rest of the day.
Remiel will be fought early in Naoya/Kaido's route, while in Amane's body. In Yuzu's route, he is fought along with Izuna, Sariel, and Anael in the last battle. Defeating him in either of these routes unlocks him for fusion.
On the 8th Day of Naoya's route it is mentioned he is an observer angel and his disappearance during the 8th Days means he has returned to heaven to prepare God's Thunder, which can incinerate the world and demons who might try to enter Heaven.
Devil Survivor 2
"One of the seven archangels serving God. His duty is to spread their instructions. The words he conveys appear as visions to people. On the day of judgement, he knows which souls will be saved and which will be destroyed. His duty is to guide the souls that will be saved."