An Oracle. Someone who met an Eldritch deity, and even when given the gift of knowledge beyond comprehension, she didn't go insane.
Because of this, she can see time the same way this deity does. However, she's only a three dimensional creature looking into the fourth. She sees it all, but can only understand it the way that three dimensional beings do, for we cannot walk through time. Her ability is like the shadow of a hand against the wall, a facsimile. And like the shadow who cannot interact with the third dimensional world, neither can she interact with the fourth.
It comes and goes in waves. Most days it's like a wave softly lapping the sands of a beach, like a gentle hand caressing the face of the earth it loved so much.
She could be walking on the sidewalk, or at the grocery store when something strange would appear. Like someone walking through the wall in clothing that's completely inappropriate for the era they're in, or she's seeing the simultaneous growth and decay of the apple in her hand. It would last a few minutes at most, and would normally leave her feeling a little uneasy. These she could handle.
Some days it felt like the same ocean, in all its anger, battering against the side of a rocky cliff at the height of a storm. As if it wanted nothing more than to sink the earth into its depths, trying to accelerate its singular mission of eroding and erasing it from existence.
During these occasions, it's quite hard to know where she is. It's like standing in a hologram of a different time, spliced on top of the present seamlessly integrating into each other. Usually it's easy to differentiate what is from a different time, especially if she's seeing the distant past or future. It does take a little time to differentiate things, but she can be sure that the horse-and-buggy about to crash into her, although a little scary, cannot hurt her in the modern city.
But it's not always that easy.
Once she stood in front of a building that she swore was on fire, only to see the fire trucks harmlessly pass through the cars stuck in traffic. Another time she saw someone being mugged and stabbed in an alley outside of her apartment, but stopped at her attempt to call the police when she saw two people walking through the corpse. To this day, she still isn't sure which the present was in those scenarios.