Disclaimer: I do not own these characters. But I sometimes play with them when no one's looking.
"How long has he been like this?" snapped Snape, quietly closing the door behind himself, rearranging his leather bag of 'special' potions until everything was back in pristine order once more. The heavy-lidded woman, dark of hair and even darker of soul, crossed her arms over her chest and huffed at him.
"Ages. It happens for about a day once a month, every month. He's…" she lowered her voice and manoeuvred them both away from the room. "He gets irritable. I mean, more irritable than usual. And wistful. Sometimes he even looks a bit, well, teary."
Snape sneered. He was not feeling particularly scathing, but after so many years of hating everything, his face just fell naturally into that expression. He was actually thinking extremely hard.
"Bellatrix," he began softly, rightly considering that he should choose his words very carefully. "This is not an area with which I enjoy a great deal of familiarity, but the symptoms which you describe are somewhat reminiscent of one particular disorder." He held his breath. Bellatrix's natural disposition wavered between painfully playful and openly homicidal, making dangerous suggestions about her master's was not something she would take lightly. Likewise any reference to menstruation which could be taken as a slight on the rationality of womankind. Mentioning both in the same sentence was Longbottom-stupid. For the moment, however, he appeared to be safe, as she was merely gaping at him with a furrowed brow.
"What are you trying to say?" she demanded, but made no apparent move towards her wand.
"You are female, are you not, Mrs Lestrange?" he smirked. They glared for a few minutes. Severus won. She glanced away, sinking into one of the kitchen chairs.
"Yes, but he isn't," she muttered, almost to herself. Snape could not quite repress the shudder which manifested at her tone of utter conviction. Ugh. How could she? In fact, how could he? He made a mental note to be sick later on, in the safety of his own dungeon. "It's definitely not the phases of the moon, I checked," she continued.
"Could it be something to do with Wormtail?" suggested Severus, sitting down opposite her with his features schooled into indifference. He was almost certain she was convinced of his loyalty after overseeing the Unbreakable Vow, but he was no fool. Having a good few feet of stout oak table between oneself and Bellatrix was never a bad thing. "He was the one who gave his flesh for the resurrection spell." The sycophantic Griffindor weasel that he is, he added to himself.
be," she snarled. "The rodent is the most pathetic of us all. His
flesh may contain all sorts of unpleasantness."
"Bubonic plague, for example," Severus agreed. He rubbed his long, stained hands together. This was a perfect opportunity to go and torment his house guest.