The first time the apocalypse came, it was the death of her race, and it came over a period of years. It began with a war that she thought her side could win, and continued through death after death until there was no one left she loved, and in fact she thought there were none left she didn't hate, and she wanted to burn it all down.
She brought the apocalypse, then. As her friends and her love had been slaughtered, so she slaughtered her own kind in return, bringing in hordes of warriors from another world. Her hordes were weak and easily killed, but there were so very many of them, and she'd given them the weapons she need to set the world afire. The flames burned everything down, and she laughed, and screamed her war cries of vengeance, as her people died.
But in the end, she was given a choice.
She could burn it all down with fire. Or she could wipe the entire slate clean, start the war over and win it bloodlessly, restore the dead to life. And all she had to do was commit a crime her people considered anathema, because it risked the destruction of the entire universe. And trust herself and her memories to a woman of an inferior, primitive species, a woman she had once thought a rival, a woman she didn't even like. And give up her quest for vengeance.
It was the quest for vengeance that was hardest to accept. She could accept potentially causing the destruction of the universe; when her world, her people, were dying at her hands, what was that? She could accept trusting a being she considered inferior; what had she left to lose? But to accept that those she hated would live again as well, that their crimes would be as undone as the death of her love and they would never be punished for what they had done in this time... That was the hardest thing to choose.
In the end, she did choose it. She gave up vengeance, gave up fire, in favor of erasure and oblivion. She sent a mortal woman back in time with her memories to hit the reset button and undo everything, and if paradox should ensue, she thought, let it come. The self who had not seen everyone she loved die would deal with it.
The second time the apocalypse came, she thought it was the paradox she had caused that was breaking the universe, and it broke her.
Her love was not dead. Her people still existed. She remembered their deaths, memories carried to her by a mortal woman so she could undo the time and change the future, but she had changed it, and it never happened. Now she had a child, a little boy she loved as much as she loved anything. And if her people were cold to her for what she had done to end the war, well, it was better that than the fate they'd suffered in the other time, and better that they be cold to her than that they know what she'd done for their sake.
She believed she'd fixed everything. Her life was idyllic. And then the universe ended.
Her son was torn from her, her love lost behind her, and she stumbled through a nightmare world of denial and rage searching for them - searching in particular for her son, who was small and young and helpless - until an ex-lover of hers taunted her with the words she could not endure - "your love is dead. Your son does not exist. He never existed. All of this is your fault."
And with that, she believed. The universe was disintegrating, and it was the fault of the paradox she'd created. Time was snapping back into place. Her love was dead because he had died in the first apocalypse, and what she had done to undo it never happened - including the birth of her son. Her son had never existed. And her attempt to save the universe had destroyed it.
Blinded by her grief, she gave into despair, and died, and death was a relief.
The third time the apocalypse came, she remembered what had happened the first two times.
She had undone the first apocalypse by agreeing to let go of her revenge. She had succumbed to the second apocalypse by blaming herself, despairing, and giving in... but her love had stopped it by screaming a challenge at the creator of the universe, by defying death until the last. Evidence bore out what she had always believed. The end of everything must be faced bravely. The Valkyries must ride during Ragnarok.
So the third time the apocalypse came, when a child another self from another timeline had created attempted to draw time in on itself and suck all of everything into the negentropic chaos at the heart of creation, she fought with a scream of defiance, with all her skill and all her violence. She poured all the pain and rage that millions of years of living with her own damaged places had given her into the fight, and she gave her life to seal the vortex that was tearing reality apart. And as she died, she laughed in the face of death, knowing that the children she, her own self, had created, would live, even as her alternate self killed that self's child, the author of this chaos, and wept.
She never expected to survive any of the apocalypses. She had not expected to survive the third one, either, but her children brought her back, teased the threads of her essence carefully out of the chaos she'd plunged into, and recreated her. She was, perhaps, not exactly the same entity. Or perhaps dying nobly to save lives instead of avenge the dead had finally purged some of her pain.
The fourth time the apocalypse came, she and the others had seen it coming for billions of years, as the universe slowly, slowly wound down. She was unimaginably old, as were her children, as were her children's children and all of their descendents, and they had held the universe together as long as they could. But all good things must come to an end, and they had long known the end was coming. All other life in the universe had finally winked out by the time she and her family, the few left remaining of her kind, stood together in the cold of the void, hand in metaphorical hand, and faced the end together.
She did not expect to survive this apocalypse either. But she hadn't expected to survive any of the others, and yet she had. As the energy ran out and nothingness froze her into unchanging crystal perfection, perfectly orderly and perfectly dead, she wondered if there would be anything on the other side of oblivion.
Notes: the second apocalypse comes directly from "I, Q" by Peter David and John de Lancie; the third apocalypse is inspired by "Q-Squared" by Peter David, though obviously refers to a different specific event; the fourth apocalypse was inspired by the fanfic "From Me To Q" by Julia Houston. Only the first apocalypse is all mine.