I recall there maybe being words of "saint" "nun" or "immortal" in the title.

The story is about a man who meets a woman (who has memories of billions of years) on either a ship or a train. He speaks to her, and she tells him her story. She says that has basically been there since the very beginning of creation, and that this one time, there had been a folklore created from her. One about a nun who seemed to know everything. They part ways sometime after that, and it was years later did he meet her again. This time, at the train station. He notices her standing with her child, and he makes an attempt to approach her. Though the child looks at him and shushes him.

It turns out that she was the child, and that her memories transfered over to her next body (while the mother no longer knew). He seemed content that while he wasn't able to hang out longer with her, he was somewhere in that billion year history.

If anyone knows the full title of this story, that would be helpful and thank you for reading!

Memories of Emanon

Oh my god yes, thank you so much.