First appeared in her collection, Peripheral Vision. It was up for the Nebula and Locus Awards and reprinted in a few major retrospectives by Ellen Datlow, Terri Windling, James Morrow, James Patrick Kelly, John Kessel.
Fowler will depart from true history, so before reading the story, it would be useful to know a little background about Albert Einstein, his first wife Mileva Marić, and what was probably their first child, Lieserl (I have edited the text only to show the things that Fowler refers to) [from Wikipedia]:
"Einstein's future wife, Mileva Marić, also enrolled at the Polytechnic that same year, the only woman among the six students in the mathematics and physics section of the teaching diploma course. Over the next few years, Einstein and Marić's friendship developed into romance, and they read books together on extra-curricular physics in which Einstein was taking an increasing interest. In 1900, Einstein was awarded the Zürich Polytechnic teaching diploma, but Marić failed the examination with a poor grade in the mathematics component, theory of functions....
"With the discovery and publication in 1987 of an early correspondence between Einstein and Marić it became known that they had a daughter they called "Lieserl" in their letters, born in early 1902 in Novi Sad where Marić was staying with her parents. Marić returned to Switzerland without the child, whose real name and fate are unknown. Einstein probably never saw his daughter, and the contents of a letter he wrote to Marić in September 1903 suggest that she was either adopted or died of scarlet fever in infancy.
"Einstein and Marić married in January 1903. In May 1904, the couple's first son, Hans Albert Einstein, was born in Bern, Switzerland. Their second son, Eduard, was born in Zurich in July 1910. In 1914, Einstein moved to Berlin, while his wife remained in Zurich with their sons. They divorced on 14 February 1919, having lived apart for five years."
Summary and Commentary (the story cannot be spoiled, but I do discuss the whole story, so caveat lector):Where Fowler departs from the above supposed facts is Einstein's mother suggests that their relationship would not be a good and not get involved with Mileva. She "plays tricks." Whatever tricks these are, if any, Fowler does not directly suggest. Perhaps there is no trick and Einstein tricks himself for believing there is a trick. Or perhaps the existence of Lieserl is a trick. Perhaps she never existed; or if she did, maybe she was given away as the above text suggests. However, in terms of the story's greatest impact (even if it did not occur this way in real life), we should probably assume that there is no trick.
Mileva is an infinitely patient lover/wife. She understands Einstein is a busy, important scientist and leaves him to his studies in an apartment away from Mileva and Lieserl. She mails letters on schedule, talking about their daughter, Lieserl, and about how she grows up. The letters are the best part of the story. They are heartbreakingly cute, detailing how the daughter loves her papa:
"Papa, papa, papa, she say. It is her favorite word. Yes, I tell her. Papa is coming....
"I am not interested in boys, she answered. Nowhere is there a boy I could love like I love my papa.
"Have I kept her too sheltered? What does she know of men? If only you had been here to advise me."And so forth. By now, you know the heartbreak. Fowler's Einstein never visits his daughter. He misses everything, from holding his daughter as a child to helping her choose a man. Einstein passages about himself are comparatively (and probably designedly) boring. Oh, Einstein! the reader says sadly.
I used to have problems with writers using real people as characters, especially if it has something negative to say, but now I now I look at these as creations. This is not the Einstein of reality although there may be men like Fowler's fictive Einstein, and that's the point.