Danny Moreno is the younger brother of Jesse Moreno, introduced and fleshed out in "The Daria Database". Like Jesse, he plays guitar - since he's teaching Jesse diminished chords, he may be better at it than his brother.
He's the "recording secretary of the Mystik Spiral Fan Club", meaning he writes the irregular newsletter and guides to their tours.
Danny's dream is to become the fifth member of the band, and thinks two of the others would definitely vote for him; he's got "a LOT of song ideas", as he tells the mailing list. A year later, on the Mystik Spiral web site's fan club section, Danny went unnoticed and Trent was running it - did Danny leave in a huff when he wasn't let in?
A Gender Swapped version, Dani, is a recurring character in DIsaac's "Rude Awakening."
Danny's involvement and departure is shown in "Ow! My Ears - The Mystik Spiral Story" by Charles RB.