The origin story that says that Evil Chicken was summoned accidentally in the 'Days of the Mahjarrat' just became a lot more interesting, due to a peculiar reading of Gielinorian history.
The days of the Mahjarrat began in the First Age, which itself ended about 8,200 years ago. Icthlarin, God of the aspects of death which lead to new life, brought the Mahjarrat to the realm of Gielinor to serve as his Stern Judges. He had delivered them from their own tortured realm of Freneskae, a world of total and unending war. That such powerful beings such as the Mahjarrat would flee their world into the arms of a god which they would later speak of as, "the fool who wished to enslave us," speaks volumes of the horrors of Freneskae.
The oath of allegiance they swore to Icthlarin failed to keep the horror of Freneskae from spreading into Gielinor. The histories are unclear, but it seems that at least one consequence of the violent behaviour and habits of the faceless Mahjarrat was the corruption and madness of Icthlarin's sister. The goddess Amascut, who was the aspect of life which caused death, became broken, became The Devourer, The Wanderer, Goddess of Destruction.
The god and goddess of the cycles of life and death were no longer balanced, but eventually, Icthlarin became what he is today, God of Death, God of Rebirth, Guide to the Afterlife, Protector against the Devourer, who only wishes for the destruction of both the body and the soul. Eventually balance was restored, but not for many centuries.
It was during this time that the Mahjarrat aligned themselves to The Empty One and the First Age ended. Even the Empty Lord, Zaros, is described by some sources as being a benevolent god before the so called 'Age of the Mahjarrat,' but the beginning of the Second Age is marked by a sudden surge in Zaros worship and the expansion of an empire guided and ruled by The Empty One and his dreaded army of Mahjarrat.
It was during the Second Age, while the tortured cry of Amascut echoed through the world, that the stories about Evil Chicken start. It is then, in "the times of the Mahjarrat" that the earliest tales describe
"a mad mage, who attempts to summon a demon and bind it to his will. Unfortunately his spell failed and all that appeared was one confused chicken. In a fit of anger at his failure the mage banished the chicken to the abyss. The chicken however appears to have survived and grown in power. Years later, when the mage cast another spell of summoning, the chicken appeared! The story does not tell of what became of the mage."
-- Book on chickens
This reading of history is particularly exciting, because it sheds light on what Evil Chicken may actually be and why he is worshiped as a god by some. He may in fact be the part of Amascut that she lost when her sanity was shattered by the actions of the Mahjarrat and her brother, Icthlarin. It would explain his ability to lay eggs, some of which may be fertile, based on the similarity between him and the dreadfowl, which at times claim to have been 'mothered' by an entity they call "the Strongest Father." The ability of this particular rooster to do what only females can may be because he is part goddess. Or it may be that Evil Chicken came into existence due to the adjustments Icthlarin had to make to fit into his new role as his sister's opponent rather than collaborator. Either explanation would fit with the reports going back thousands of years of Evil Chicken's stubborn refusal to stay dead. What is death to something created, perhaps inadvertently, by the gods of rebirth?
It raises a troubling theological issue, though. What if Evil Chicken is Amascut's call for justice? After all, he takes a form very similar to Lord Armadyl's favored creatures, the Aviantese. If this is so, are we to allow him to do as he pleases, since he may be serving the Lord of Justice?
It is unlikely, though, for Evil Chicken has been wreaking havoc and killing seemingly random people for nearly 7,000 years, if the stories are to be believed. How does what he has done so far serve justice, and why has the debt taken so long to be paid?