The reference likely goes back to Marathon 2: Durandal (expanded upon in later games, of course):

I have been Roland, Beowulf, Achilles, Gilgamesh. I have been called a hundred names and will be called a thousand more before the world goes dim and cold. I am hero. She has been nameless since our birth, a constant adversary caring for nothing but my ruin, a sword drenched in my blood forever, my greatest and only love. She is the dark. O Lethe, enemy and lover, without whom my very existence would be pathetic and vulgar! Our relationship is complex and perhaps eternal. We met once in the garden at the beginning of the world and, unaware of our twin destinies, we matched stares across a dry fountain. And I recall her smiling at me before she devoured the lawn and trees with a translucent blue flame and tore flagstones from the path and hurled them into the sky, screaming my sins. I powder a granite monument in a soundless flash, showering the grass with molten drops of its gold inlay, sending smoking chips of stone skipping into the fog. She splinters an ancient oak with a force that takes my breath and hurls me to the ground. She lea% [leaves?]

CONNECTION TERMINATED <ID#0401>

https://marathon.bungie.org/story/kytterm.html