Helel is his judaic/hebrew name and means Morning Star (like the strong Almighty Spell he wields). It´s thought-provoking how the Lord of Darkness has 3 different incarnations in P3: FES and wields the ultimate spell in the whole game through.
Moon Social Link is Gourmet King, funny guy.
Also, here is my spoilerish speculation about an ultimate social link, DO NOT read if you haven´t finished the game thorougly! : The World Arcana social link actually exists in P3: FES and is Elizabeth. She asks you to go out with here and in the end you can accomplish your relationship as a pair like with Yukari, Fuuka, Mitsuru, Chihiro and Yuko. However she hasn´t found the answer to her existence like it happens with the other social links, so she challenges you to battle and, after defeating her, gives you a present like all the other MAX social links do. Since The World Arcana is based upon the completion rate of the other social links, there´s no need for an Arcana rank-up. And Since Orpheus Telos represents the endless possibilities and fullfilment of one´s self and purpose, similar to what Elizabeth tells you before fighting her about Igor and yourself, I would actually put him under The World Arcana (same thing says Igor when he fuses "The Universe" Arcana). As a note, The Fool Arcana represents malleability, being able to evolve as one wish through bonding (social links) which ultimately leads you to The World Arcana.
