Shepard always lies about what happened on the Citadel.
Even to himself.
To be fair, he's not entirely certain it wasn't a hallucination brought on by blood loss and head trauma. When they found him.. when *Kaidan* found him (Distantly, Shepard felt the roll and crash of Kaidan's biotics like waves through the darkness, and somehow the Major had read the ripples back)… he was pinned in a pile of twisted wreckage, alien and human architecture too broken to sort apart.
And nearly dead, he dreamed.
They were the worst sort of dreams : blood and death and the ghost of a child was forcing him to make a choice no one person ever should. And maybe because he thought he was dreaming, or hallucinating, Shepard chose differently.
Out of three, he'd made one.
He remembered something Javik had said, that every soul to ever be born was watching this moment, and as the ghost shouted at him to choose, he thought he could feel them.
Biotics dancing across a billion-year web of life like a careful spider, not warp and slam and throw, but a single pull, woven from all of that, every bit of life that had ever looked up to the stars. Alien metal had torn and wrenched, screaming like the ghost of a child screamed at him. After all, it was a dream. And in this dream, broken and battered, Shepard let himself believe, just for a moment, that he was that biotic god they'd joked about.
A wind sweeping history clean.
He took the ghost's power too, the simulacrum of life that it had clung to for countless cycles, and with all of that singing in his nerves, Shepard had stepped into the light.
And then he wasn't the spider, pulling on the web.
He was the web, and the galaxy was laid out beneath him like a tray of diamonds as the light spread out from him. He was the Citadel. He was the Crucible. And He was the Catalyst.
He gave the Reapers a choice. The first choice they'd ever had. (Leave or Die) and he could hear them.
He could hear *everything*.
He *was* everything.
And it was more than he could bear.
And it tore him apart until he was nothing at all.
And he drifted there until he heard Kaidan calling him home.
They tell him, much later on, that the sky had looked like it had been made of diamond for a moment. White light with flashes of red and green and blue dancing across the clouds like lightning. Every VI, AI and synthetic had suddenly hard-rebooted. Starships had hung helpless in orbit as their computer systems crashed, then sputtered back, and the relays had flared like suns all across the galaxy before going silent and dark.
And the Reapers? Those that hadn't fled back to the stars had dissolved, flaking bits of biomatter and synthetics unhooking from each other. Deconstructed down to the molecular level.
And they ask him – the doctors hovering around his bed when he first wakes up, the therapists the Alliance sends, the higher ups from countless stranded alien governments – what happened? How did the catalyst work? What did he do, after Hackett contacted him?
He always lies and feigns amnesia. Reminds himself it was a hallucination, because the more times you tell yourself a lie, the more it becomes the truth.
(The first time they asked him - some over-eager Alliance medical officer pushing Shepard, scant days out of the month-long coma - he *did* remember, and he'd leveled a section of the hospital, screaming like alien metal and the ghost of a child in an uncontrolled power flare before they were able to get Kaidan to him. Kaidan who had sat by his bedside, growing a beard and dark circles under his eyes, and who read to him, *sang*to him in that raspy voice, knowing that Shepard could hear him. The love of his life who did not deserve the hell of Shepard's memories any more than he did himself.)
And if a flash like diamond light skitters behind his eyes like a spider sometimes, and he drops his fork or loses his place in a conversation, it's ok, because he had blood loss and head trauma, and even someone as tough as Shepard takes a while to heal.
And when they ask him, years later, what happened? He quirks a faint smile and lies.