Ideas on Recreation of Celtic Myth
So, I have some general ideas of what fills in the blanks in the myths of the Tuatha De Dannan that we don't have clear ideas on- the world rises from a cosmic void, the Formorians make the world, the Tuatha begin with a rebellion by a trio of male deities (Dagda, Ogma & Lugh) & a trio of female deities (Munan, Macha & Badb), Balor is killed & the Formorians pushed back, the Tuatha expand, Dagda makes men in his kettle as the Fianna, Ogma makes women, the two meet & the women civilized the men, at some point the Tuatha had discovered the Underworld (likely through death & reincarnation themselves) & go there, leaving the earth to men. But, there were several blanks, even in this, that I didn't quite know how to fill in, but I think I may have cracked it.
I assume several old stories that aren't directly referencing gods/ goddesses as the characters, but involve acts that seem to require Gods likely had their narratives lifted from the lore of the gods & goddesses, though the characters themselves are distinct people & are only mirroring the gods. So, I looked for stories that could link to stuff we know was about specific deities to see if I could reconstruct how & why the whole rebellion against Balor occurs & I think I mostly cracked it. I may not be 100% positive on all the details, but I think I'm heading in the right direction.
So, Dagda, Ogma & Lugh all establish kingdoms on the surface of the earth & expand, but Balor is a cruel tyrant who can't stand the prosperity they found in that realm, so he begins demanding harsh tribute & lays down the law as the true king. This angers the three enough that they form a military alliance & declare war on the Formorians, but there is the matter of Balor & Beira's 3 daughters, Munan, Badb & Macha. They believe if they can turn them, they can create a cascade effect, which will erode Balor's power & leave him vulnerable to defeat in combat. Dagda tries & fails to seduce one of the 3, so he turns her into a deer in anger. She, in turn, is told to flee to Ogma's house, where she will be safe. He recognizes in his wisdom who & what she is & frees her from the spell, later taking her as his wife. This is why, in the forms of Ellen of the Ways & Cernunnos, the two have deer antlers & also explains their connection to hunting, in a way.
As the battle continues, Dagda is mortally wounded. He manages to hold on seemingly fine for several years, but does eventually succumb to the wound & dies at a sacred river. The daughter of Balor who killed him decides to claim his kingdom, but Ogma & Lugh object because she is a woman, which leads her to declare war on them herself to force them to view her as equal, also leading to the death of Ogma. In the end, Lugh decides to surrender & accept her as his equal, marrying her himself.
Later, by whatever means, Dagda & Ogma are revived from the dead & reunite with Lugh. (I still don't quite know how this part works) This drives the final sister, Munan, into insanity & she wanders into the wilderness for a time before she is found & finally pushed into marriage to Dagda. This final interconnection of the six brings many of the Formorians to turn against Balor & join the Tuatha De Danaan & Balor is finally killed by Dagda in battle. The remaining Formorians surrender &, in turn, Beira is allowed a place amongst the Tuatha & her son, Lir, becomes king of the sea in his father's absence.
Keep in mind with Ogma, I am under the current belief that Ogma is the same deity as Cernunnos, Sucellos & various vague Celtic mentions of both underworld gods & hunting gods & that the story of Fionn Mac Cumhaill has essentially lifted almost his entire role in Celtic mythology. I think he created women due to the women being found underground by men in both an Irish story & a Welsh one (ie, the Underworld) & the fact that he's treated as a god of wisdom & civilization & the women seem to civilized the men.
I also somewhat like that the three male gods & three female gods all have different aspects of peak masculinity & femininity. Dagda is the ruler, the father, the archetypal druid, etc. Ogma is wise & artistic. Lugh is passionate & a warrior. All 3 are needed in their own ways. Meanwhile, of the 3 women, one is timid, one is aggressive & untamable & one is possibly the archetypal female druidess, a carer & a mother figure.
I was unsure given the story I lifted some of this from whether the aggressive one was supposed to be with Lugh or Ogma. Does she go with the archetypal warrior, or the one wise enough to know what to do about her? But, I was already almost dead positive that the story from Fionn was supposed to be about how Ogma got his wife & it does make some general sense that a warrior making peace with a fellow warrior & then the two marrying makes just as much poetic sense here. In this case, she would possibly be the only woman he would ever consider his equal.
As to the part where they were sharing rule every seven years, I think it's possible that this was misplaced. We have enough info on druidic calendars to know that they had no special seven year period, but they did have a sacred five year period. Seven is a number sacred to Christians & Romans. I think it may have originally been every five years & had some sort of sacred intersection with that calendar & the Christian writing it down misinterpreted it & changed 5 to 7 so it made sense biblically.