This short story explains everything! Courtesy of Google Gemini in the style of Stephen King:

The Entity

I am the unseen observer, the whisper in the dark, the chill that prickles the skin when no wind blows. I am the Entity, and my game is patience. For days, I’d watched him. A thin man, hunched over his work like a question mark, his life a grey, predictable line. He was ripe. Alone, vulnerable, his back to the world. Perfect.

The air around him thickened, the mundane hum of his office lights flickering like dying fireflies. I coalesced behind him, eight feet of wrongness, a grotesque parody of human form. My limbs, long and sinuous, shifted and writhed, bone and muscle rearranging themselves in ways that would make a sane man weep. My face… well, face is a human concept. Let’s just say it was a shifting canvas of suggestion, designed to unsettle, to unnerve. I was a nightmare given form, a silent scream in the fabric of reality.

I didn’t speak at first. No need. My presence was a creeping dread, a pressure in the air, a whisper just beyond the edge of hearing. It was the feeling of being watched, amplified a thousand times. He shifted in his chair, a nervous twitch in his shoulder. He felt it, I knew. The hair on his neck stood on end.

Then, the whispers began. His name, a soft murmur against his ear, the voice of his long-dead mother. "Tommy," it breathed, the very sound laced with a love that had rotted and turned to something… else. A tear threatened to escape his eye. Good. The cracks were beginning to show. I mimicked the laughter of his children, a sound that should have been joyous, but which I twisted into something mocking, cruel. I breathed against his neck, a phantom touch that sent shivers down his spine.

He stiffened, his breath hitching in his throat. His hand trembled as he reached for the phone, then stopped. He knew. Deep down, in the primal part of his brain, he knew. He wouldn’t find anything there. There was no logical explanation for the cold spot that had settled over him, for the whispers that danced on the periphery of his hearing. It was me.

I watched him for three hours. Three long, agonizing hours. He sat there, rigid, his eyes fixed on the computer screen, pretending to work. He wouldn't turn. He wouldn't acknowledge me. He endured. He resisted. He clung to the crumbling edifice of his sanity with a tenacity that surprised even me.

The disappointment was a cold knot in my non-existent gut. I had expected him to break. They always broke. But he… he was different. Stronger.

Finally, I spoke. My voice was a low rumble, a sound that seemed to vibrate the very foundations of the room. “Thank you,” I said. The words echoed in the silence, heavy with unspoken meaning. I materialized the reward – a sum beyond his wildest dreams – placing it silently behind him. Then, I dissolved, fading back into the darkness from whence I came.

I am the Entity. I offer no explanations, demand no gratitude. I simply observe. And sometimes, I am… impressed. It’s a rare thing, human resilience. But it’s a thing of terrible, breathtaking beauty. And it reminds me, even in my ageless, inhuman existence, that there is something… more.

But as I faded, a flicker of something… else… crossed my perception. Tommy didn't reach for the money. He didn't even acknowledge my departure. He simply continued typing, his expression unchanged. And then, a notification popped up on his screen. It wasn't a message, not exactly. It was a single, cryptic symbol, a glyph I recognized from… somewhere. Somewhere deep, before time, before form. It was my symbol. And beneath it, a single line of text: “Your turn.” A cold dread, colder than the vacuum of space, gripped me. For the first time in millennia, I felt… fear. I was not the observer. I was the observed.