Morrigan is a trifold Goddess, a Goddess in three parts a shapeshifter, and a warrior. She is basically a goddess of battle, strife, fertility and sexuality. It has been speculated that the French phrase for orgasm (le petit mort, literally, "the little death") is a carry-over from the Celtic past of France (as is true for most of the European sub-continent). Morrigan as in all Celtic Goddesses is the balance of good and evil. Like the Greek Goddess Athena, she often steps in to wage justifiable war. She is called upon by warriors, and if she agrees with their battle and motives, she aids them.
War was always important to the Celts; they loved to fight and built whole cities around schools of warfare. They were fierce warriors who even cowed the Romans for a time. Women fought with men at times, and it is reported that Celtic women, when sending their men off to war, told them come back carrying your shield or on it." In effect they were saying " win or die".
The Celts looked upon Morrigan as the goddess who brought honorable death so there could be rebirth. She led the armies, brought death, but brought life as well as her role as a fertility goddess. She was the symbol of life, not never ending death. She is not evil but dark. She is the symbol of the wheel of life, the concept of birth and death, interlinked in a cycle continuos throughout time.