Title: In the Reckoners alternate universe, why did David’s father kill him?
Tags: parallel-universe;the-reckoners
Question: In the book Calamity, David (the books narrator and protagonist) goes to a universe where Calamity has vanished, and some of the epics are good, some are bad.
The first person he meets there is Firefight, an epic who uses fire. He tells him that the epic who David killed in the first book, Steelheart, killed him in this universe. David also sees him going to save some people on top of a skyscraper, while in the main universe Steelheart is a mass-murdering bully.
Later, it turns out that the alternative Steelheart is actually David's father in the other universe.
He (the dad) then says (not quite exact quote)"I killed you. I tried to save you, but you still died."
My question is this: Why did David's dad kill him, and how? Killing someone is rather hard when you are trying to save them, so this line has had me confused for quite some time.

Here is the accepted answer: We don’t know
Here’s the quote referenced in the question:
I released over a decade of pain and sorrow, a decade of loss. He held
me tight, and he smelled like my father, Epic or not.
“Son,” he said, clutching me, weeping. “I killed you. I didn’t mean
to. I tried to protect you, to save you. But you died. You died
anyway.”
Calamity
It’s clear that this is not simply Blake feeling responsible for his son’s death: he actually killed him. Firefight  confirms this:
“Look, I’ve told you before that you must meet him,” Firefight said.
“He refuses to believe what I’ve seen, but he needs to talk to you.”
“Why me? What does he care about me?”
“Well,” Firefight said, “he killed you.”
Calamity
The book doesn’t elaborate on why this happened (perhaps saving it for a future series).
It’s possible that Blake killed David due to becoming an Epic and being infected by Invocation’s contempt for humanity (Invocation is the alternate-universe version of Calamity). This seems unlikely, though. People in the alternate universe talk as if the Epics there never felt compelled to evil:
And no Calamity,” I said, looking at the sky.
“Calamity?”
“The red star!” I said. “That brought the Epics.”
“Invocation?” he said. “It vanished a year after it arrived; it’s been
gone a decade.”
“Do you feel the darkness?” I demanded. “The drive toward selfishness
that strikes every Epic?”
“What are you talking about, Charleston?”
Calamity
From what little information is given, it would seem that Calamity and its brethren were supposed to give humans powers and see what happened, not influence them in other ways (as Calamity did). So in the alternate universe, Invocation did its job properly and left when its time was up, and didn’t pollute humanity with its negative feelings.
Blake’s words fit with this, too: he probably wouldn’t have described himself as trying to “save” David if he had been trying to kill him out of malice. Perhaps it was an accident; perhaps he had to kill David for some reason or another, but had done everything to try to prevent it. Ultimately, at this point we just do not know how Blake caused his son’s death.
One highly speculative possibility is that the bank scene from Steelheart happened much as it did in the main universe, but with Blake Charleston as Steelheart instead of David. Recall that government agents came in and tried to subdue Steelheart, and their bullets bounced off of him. Perhaps, in the alternate universe, Blake tried to shield his son, but a bullet glanced off of him and killed David. But this is mere speculation, albeit consistent with Blake’s statements and the general similarities between the universes.

Here is another answer: this is old but I think since calamity left a year after it arrived that meant he stayed there in the sky for a year infecting people with his contempt. so maybe when Blake turned steelheart he was like the epics in David's universe and killed david.
Comment for this answer: This is contradicted as soon as David asks Firefight (from the parallel universe) about calamity, and feeling "the darkness". See the last quote in the other answer.

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