The Agueda and young man from the first part of the story are the same persons as the Don Badoy and his dead wife from the end of the story.
The story makes a few jumps in time, dividing the text into four parts:
- May 1847: the young Agueda goes to the mirror. This part ends with "he heard a step behind her, and a smothered giggle, and instantly opened her eyes."
- Presumably years later: a young girl asks her mother, Doña Agueda, about what she saw in the mirror.
- May 1847: the continuation of the first part: how the encounter between Agueda and Badoy Montiya ended.
- May 1890: Don Badoy Montiya's grandson wants to see his future wife in a mirror; this reminds the old man of a time in May, when he was still young, when he himself had stared into that mirror.
The connection between the first and the second part is established by the beginning of the second part:
"And what did you see, Mama? Oh, what was it?" But Doña Agueda had forgotten (...)
Doña Agueda from the second part is Agueda from the first part, many years later. Agueda from the first part had expected to see in that mirror either her future husband or the devil. Doña Agueda says she saw the devil; this devil had mustaches and the same scar as her daughter's father.
The connection between the second and the third part by the transition between these parts:
"And did he speak to you, Mama?" "Yes… Yes, he spoke to me," said Doña Agueda. (...)
"Charms like yours have no need for a candle, fair one," he had said, smiling at her in the mirror (...)
In the third part, we learn that Badoy Montiya had just returned from Europe, that he is drunk and that he wants to dance with Agueda. But Agueda wants to get away from him and when he does not let her pass, she bites his hand and runs away. Badoy swears he will have his revenge but also realises he is in love with her.
In the last part, Don Badoy Montiya has forgotten about the incident until he glances into the sala again and
he shuddered, he stopped, his blood ran cold—for he had seen a face in the mirror there—a ghostly candlelit face with the eyes closed and the lips moving, a face that he suddenly felt he had seen there before though it was a full minutes before the lost memory came flowing, came tiding back (...)
This description is one of several passages that connect the fourth part with the first and third parts. In the third part, Agueda "shuddered in her white gown"; in the first part, she had stood in front of the mirror with her eyes closed and "whispered the incantation". Don Badoy remembers he had seen this shortly after he had returned from Europe.
Other connections between the fourth and the first part are the "roofs looming like sinister chessboards" (literally repeated in both parts), Don Badoy's tears while standing at the window, "the clackety-clack of the watchman’s boots on the cobble and the clang-clang of his lantern against his knee" (literally repeated) and the watchman's song ("Guardia sereno-o-o! A las doce han dado-o-o.", also literally repeated). Based on this, there can be no doubt that Don Badoy Montiya of the fourth part is Badoy Montiya from the first part, 43 years later.
How do we know whether Doña Agueda was Don Badoy Montiya's wife? The hints for this are more subtle. First, there is the following exchange between the grandson and Don Badoy:
"It was just foolishness, Grandpa. They told me I would see my wife."
"Wife? What wife?"
Don Badoy's reaction makes most sense if thinking back to May 1847 had made the old man think of his own wife.
Another passage provides a clearer indication. When the grandson asks, "Was it of the scare that Grandma died?", Don Badoy realises that (emphasis added)
[f]or a moment he had forgotten that she was dead, that she had perished—the poor Agueda; that they were at peace at last, the two of them, her tired body at rest; her broken body set free at last from the brutal pranks of the earth—from the trap of a May night (...)
The words "they were at peace at last, the two of them" makes most sense if Don Badoy and Doña Agueda were married. The alternative theory, that Doña Agueda's daughter got married with a son of Don Badoy's (none of the man's children are mentioned in the story), is less likely, since there is not a single hint in that direction. The story implies that Badoy (Agueda's "devil") and Agueda (Badoy's "witch") did not have a happy marriage.