Morrigan's History
One of her origins is that she is a Goddess of Death and Battle, and has existed since Death itself, taking many forms and names since then.
Another origin of hers is Morrigan was seemingly the daughter of Iarbonel and Gaea/Danu, and the sister to the Dagda, Leir, Nuada, Ogma, Badb and Macha.
Morrigan married the Dadga and was the motherof his eldest son, the war god Bodb Derg. She was not the mother of his second son Lugh, mothered by Ethniu.
Hyborian Age
Morrigan was one of the many deities worshiped in Hyboria, invoked notably by Cimmerians, along with Nemain and Macha, as part of the "triple war goddesses".
Next Incarnation
In the 1st century AD, Celtic druids Taliesin and Moiragh were mortally wounded in an attack on their village by Roman legions. As they were dying, the druids offered themselves as a sacrifice to Morrigan (as well as to the Celtic gods Taranis and Cernunnos) so that one day a warrior would be born to exact vengeance upon evil. In response, Morrigan, Taranis, and Cernunnos empowered the wooden staff carried by Moiragh (which came to be known as the "Oak Staff of the Druids") and became oathbound to one day empower a warrior as their instrument of justice on Earth.
Circa 150 B.C., after the death of her father, a girl-warrior in Ireland bargained for power from the supernatural and confronted Morrigan out of vengeance. The girl-warrior was successful in besting Morrigan, who lay bleeding out on the ground before the final blow. Before dying, Morrigan offered her power and position to the girl. The girl seemingly accepted, becoming the next incarnation of Morrigan for over two thousand years.
It remains unclear whether Morrigan is merely a title passed from one woman to the next along with the necessary power, or if Morrigan is a sentient spirit or consciousness that is hosted by these women, like a mystical symbiote.
Third Host
In 1000 AD, the Third Host of the Celestials occurred, during which the aliens informed they would return 1,000 years later to judge Earth's right to continue existing. While the pantheons prepared for war, Gaea planned a peaceful solution to the problem with many goddesses, among them Morrigan.
For the next thousand years, they searched for humans representing mankind's highest ideals, to be offered to the Celestials as an offering. The goddesses placed the candidates in suspended animation, with their superhuman potential, the legacy of the First Host, awakened.
Modern Days
In modern times, Morrigan (along with her fellow Celtic gods Taranis and Cernunnos) eventually chose American mob enforcer Kyllian Boddicker to become their instrument of justice on Earth. To that end, the three gods each possessed Boddicker simultaneously, causing him to hear their voices in his head and to manifest mystical tattoos of different Celtic symbols on his body capable of casting a variety of magical spells. In particular, Morrigan persuaded Boddicker to pursue lasting vengeance against the criminals who killed his sister. As Morrigan and the gods�?? possession of Boddicker�??s body pushed him to the brink of insanity while he was avenging his sister�??s death, Dr. Strange sensed the massive expenditures of magical force and set out to confront Boddicker. Dr. Strange eventually cornered Boddicker on a rooftop and entrapped him in the Cloak of Levitation, causing Morrigan and the other gods to briefly leave Boddicker�??s body. Dr. Strange attempted to capture the three gods with a spell of entrapment to prevent them from repossessing Boddicker, but Morrigan sent a murder of crows to attack Dr. Strange and prevent him from maintaining the spell. Realizing that he must accept his fate, Boddicker agreed to serve as the gods�?? instrument of justice on the conditions that they must assert no control over his free will and only come to his aid when summoned by him. The gods accepted Boddicker�??s terms. Morrigan indicated that she did not care about Dr. Strange�??s offer to tutor Boddicker on the use of his newfound powers, but only seemed interested in feasting on the evil souls that Boddicker would vanquish for her. The gods then bestowed the Oak Staff of the Druids upon Boddicker, who would later become the sorcerer known as Wildpride.
Theresa Rourke
After Theresa needed her power, the current host of the Morrigan was ready to die, and told Theresa the only way to claim her power is to kill her, which she did.
Dawn of The Morrigan
A new X-Factor was created due to the influx of missing mutants and unknown deaths The Five couldn't process for the resurrection protocols. Her host Theresa was one of the first mutants on their investigation list after she let out a sonic scream as she fell to her death on a Krakoan cliff.
Resurrected by the Five, her host Theresa died again 5 days later in England after The Morrigan pushed her into suicide. Upon another resurrection, X-Factor interrogated her host about her mysterious deaths, but she avoided their questions and blatantly lied to them. When Theresa left the Boneyard, she was confronted by Lorna on why she wasn't being honest, which prompted the Morrigan to use Theresa to use her powers to bewitch Lorna into sabotaging the investigation on her. As she left, a murder of crows formed in the night sky, showing Morrigan was in full control of Theresa, and not a simple influence anymore.
After being "tailed" by Daken, she lured him into the Alberta wilderness in a snowstorm to kill him without having his teammates alerted due to his loner nature. What she didn't know was that after leaving him for days to die on a wooden pike, he had a healing factor. With this (and Lorna hypnosis trance being negated because of Rachel), Northstar was able to find him within the vast wilderness in 7 mins and bring him to the Boneyard.
