What's the deal with the Shadowkeeper, exactly?

[Grimr]

I won't pretend to understand the details of the flood per say. I would just go along i with moose's explanation. Bottom line shadowkeeper manipulates the first 's heroes and obviously instead of killer her they kill the two ascians and it unleashes a flood of light. The ascians had thought by tippping the first to light it would cancel out their failure on the thirteeth.

Though it would eventually lead to a rejoining or maybe not. We were told by cat boy( sorry i can't remember his name) that the use of black rose and the first tilt towards light would create a rejoining. However the foil to this plan in this time and probably the other is zenos. Zenos wants nothing interfere with his duel between him and the wol so he destroys black rose in the current timeline and i don't see him sparing black rose in earlier timelines either. (Se wrote themselves into a corner with that one.)

Now i am sure there would be an 8th calamity but black rose would not be part of it and the first's tilt would just be an ascian failure.

[RyuDragnier]

I won't pretend to understand the details of the flood per say. I would just go along i with moose's explanation. Bottom line shadowkeeper manipulates the first 's heroes and obviously instead of killer her they kill the two ascians and it unleashes a flood of light. The ascians had thought by tippping the first to light it would cancel out their failure on the thirteeth.

Though it would eventually lead to a rejoining or maybe not. We were told by cat boy( sorry i can't remember his name) that the use of black rose and the first tilt towards light would create a rejoining. However the foil to this plan in this time and probably the other is zenos. Zenos wants nothing interfere with his duel between him and the wol so he destroys black rose in the current timeline and i don't see him sparing black rose in earlier timelines either. (Se wrote themselves into a corner with that one.)

Now i am sure there would be an 8th calamity but black rose would not be part of it and the first's tilt would just be an ascian failure.

I don't believe SE wrote themselves into a corner. Think about it, we had the upper hand against Elidibus-Zenos when we were fighting them, it was only when the Exarch interfered did we lose. It's possible we actually killed Zenos' body in that timeline, preventing him from actually being able to do anything against Black Rose. In fact, killing Zenos' body MAY have been the trigger that caused them to use Black Rose on the front lines.

[Rosenstrauch]

I think it's important to note that the Eden questline provided a cause and effect chain in regards to how, exactly, the Flood of Light began. Specifically, it was not a natural occurrence as a result of the First's aetheric balance sliding too far towards Light, but rather a willful act carried out by the sin eater Eden. Eden was Mitron, of course, and so technically speaking, Ardbert's failed attempt to kill him led to the Flood of Light. But there are degrees of separation there, and it's no longer the case of "they were too good at being heroes".

I think this change in events came about for the same reason that the Astral/Umbral -> Dark/Light development ended up happening. This may sound a bit presumptuous on my part, but I think in hindsight that "Astral" and "Umbral" ended up having two separate definitions, one in which the terms were defined by "colors" with human perspective-based morality attached to them (Light and Dark) and one in which they were defined by elemental polarity (activity and passivity). And I think the writers wanted to move away from the first definition and lean heavier on the second.

On the other hand, the light sin eaters and light buff in Eden's Verse: Iconoclasm are listed as "astral" while the dark sin eaters (yes really) and dark buff are listed as "umbral". And when you talk to Cyella about Gaia, she notes that the girl has an "Umbral presence" or something to that effect. Even though Cyella is from the Thirteenth, not the Source...

Anyways, it also made for some decent rhyming in regards to Ryne's "I'll become Shiva!" bit—Ryne and Ardbert are responsible for Shiva and Eden's creation, and those being twisting their good intentions to cataclysmic ends. And so on.

And that's not to say Ardbert and friends' actions as Warriors of Light didn't tip the balance heavily in favor of Light to begin with. That was the Ascians' plan from the beginning, after all, and it's reasonable to assume that if Ardbert hadn't gone off script, the Rejoining would have gone off without a hitch well in advance of how it ended up happening in the Eighth Era timeline.

[Vyrerus]

Eden

I don't know how it varies across localization, but in English, Mitron tells us that he and Loghrif were tasked with keeping the Light on The First in check to prevent a Flood. When Ardbert slew them, Loghrif died and Mitron remained, mutating into the first sineater. He describes himself as insensate, and his body's instincts were influenced by Ardbert's fervent desire to banish darkness, and so his body unleashed the Light that had poured into it when Ardbert and Co. mutated him with the Blade of Light.

When Minfilia stopped the Flood, Mitron regained his conscious self, but he was only able to whisper to Gaia.

While we can still say that the blame for causing the Flood rests with Ardbert & Company, his suicide and journey to the Source ultimately resulted in deliverance via Minfilia, which coincidentally put the First back on course for the Rejoining while sparing what was left. Which is also the only time that Ardbert & Co. were defeated.