The Romans left a likeness of Her for posterity--She was shown as a grotesque woman with a pale and ghastly look, Her eyes afire, Her garment ripped and torn, and as concealing a dagger in Her Bosom. Actually, most women look pale and ghastly when concealing a chilly dagger in their bosoms.
Her geneology is from the Greeks and is utterly confused. Either She was the twin of Ares and the daughter of Zeus and Hera; or She was the daughter of Nyx, goddess of night (who was either the daughter or wife of Chaos, or both), and Nyx's brother, Erebus, and whose brothers and sisters include Death, Doom, Mockery, and Friendship. And that She begat Forgetfullness, Quarrels, Lies, and a bunch of gods and goddesses like that.
One day Mal-2 consulted his Pineal Gland* and asked Eris if She really created all of those terrible things. She told him that She had always liked the Old Greeks, but that they cannot be trusted with historic matters. "They were," She added, "victims of indigestion, you know."
Suffice it to say that Eris is not hateful or malicious. But She is mischievous, and does get a little bitchy at times.
*THE PINEAL GLAND is where each and every one of us can talk to Eris. If you have trouble activating your Pineal, then try the appendix which does almost as well. Reference: DOGMA I, METAPHYSICS #3, "The Indoctrine of the Pineal Gland"