One of the very first primal beasts ever created, he is known as the supreme primarch who commands all other archangels. He was made to oversee evolution by an Astral researcher who had a keen interest in the subject. Bequeathed with ultimate power by the Astrals, he strives to protect the people of the Sky Realm. Even now, his eyes—melancholic and unsuited to an ultimate weapon—scan the blue horizon, in search of anything that might disturb the progress of the skies. Originally just a Shingeki no Bahamut collaboration summon, he becomes an important recurring character in the "What Makes the Sky Blue" storyline.
Lucifer is credited as the creator of the archangels Sandalphon and Raziel. He and Belial were Lucilius' first creations and were created at the same time. In What Makes the Sky Blue II: Paradise Lost, he is decapitated by Beelzebub so that he and Belial can harvest his body and use it to resurrect Lucillius. Overwhelmed with grief and anger, Sandalphon initially struggles with the loss but ultimately resolves to honor Lucifer's legacy. Sandalphon ascends to become the new supreme primarch, taking on the responsibilities and burden of leadership to protect the skies as Lucifer once did.
Lucifer shares a similar appearance with Lucilius and is identical to Lucio in both face and clothing, making differentiation challenging. Lucifer wears a short-sleeved breastplate with shoulder armor, elbow gloves, a thin red cloth around his neck, and a white cape. Unlike Lucio, who has two small wings, Lucifer has six large featheredwhite wings. Without wings, their personalities offer clues: Lucio appears teasing, while Lucifer is more innocent and joyous. Sandalphon is often annoyed by Lucio but blushes or appears delighted around Lucifer. Most ship art featuring Sandalphon pairs him with Lucifer unless explicitly indicated otherwise.
