All your life you held it back.
It's been there for as long as you can remember, this raging demon in the pit of your stomach fighting to get out.
But you, you were strong. You held it back, you clamped it down, you never let it show.
It was on the Bifrost that finally you snapped.
You let go. You let yourself fall, through the abyss and into whatever lay beneath.
And — you were going to die anyway, and there was no one left for you to hurt — you surrendered, at the end, you let the demon loose.
The madness crashed over you and swept you away, wild and vast as the ocean, and you let it happen; you'd been on the precipice for years and years, desperately holding on, but now both your mind and your body were falling and you didn't care.
The madness was free, and the freedom was glorious.
They wonder.
They wonder where the madness came from. They do not know that you were always like this, always broken. They did not see the madness; they saw only the shield you put in place to hold the madness back.
The shield is shattered now, and when Thor looks in your eyes he can see the shards.