Author's Note: This is a triad story. If you are uncomfortable with this, please look elsewhere. I do not own Harry Potter and am making no money from this story.

Narcissa Malfoy was having a normal day at home with her son. Draco was, in Narcissa's eyes, perfect. At four, he was adorable, and as she watched him sign his name with a wobbly quill, she felt the same pride any parent would at the small milestone. He glanced up at her with a bright smile as he finished the 'y' at the end of his name.

"Very good, my little dragon!" Narcissa praised, pulling over the plate of brightly iced biscuits. "Your 'r's are looking much better."

Draco beamed, and reached for a green dragon biscuit. Narcissa smiled indulgently, but then she noticed something strange around Draco's wrist, when the sleeve of his robes fell away as he was busily eating his biscuit.

"Draco, darling, what's that?" Narcissa asked, feeling her heart beating faster. It couldn't be. Not her son. She had seen that mark before, but never on her son.

"Nothing, Mummy." Draco said instantly, trying to hide his wrist.

"Draco, you know better than to lie to mummy." Narcissa said, voice firm despite the fact that her insides were quivering. "Let me see."

Draco's lip wobbled as he held out his hand. "Don't scrub it with...with a...scorur..until it bleeds, Mummy. I didn't mean to."

Narcissa couldn't bear to see her son so frightened. She immediately pulled him into her lap and wrapped him up in her arms, pressing kisses to her forehead. "Mummy will never hurt you, my little dragon, I promise. Why would you think I would?"

Draco buried his face in her robes. "Harry said his aunt did that, an' when it didn't come off, they locked 'im in a cupboard." He took a deep breath. "And He'mione's parents took her to a dock-tor, which sounds like a not nice place at all."

Narcissa let out a long breath. She didn't need to see the mark now to confirm it. She swallowed hard. "Mummy's not mad at you, Draco. It's not bad at all. It's magical, and very special just like you." She gave him an extra cuddle. "Now, pop off to your playroom, lessons are done for the day. Mummy must call your Great-Great-Aunt Cassiopeia."

Narcissa watched him go before putting her head in her hands on the table. A trine. They were considered exceedingly rare, though Narcissa suspected they were more common than many thought. They just rarely came to fulfillment, largely because of purebloods like her and her husband.

Trines were triad soul bonds, unbreakable and unprompted, but they only formed between a pureblood, a half-blood, and a muggleborn. The wizards and witches in question could never marry or have children with anyone else, the magic would not allow it. Nothing could contravene a soul bond. Narcissa had seen what had happened when someone tried. Cygnus Black the second had been apoplectic when he had discovered the trine symbol on Cassiopeia's wrist. He had tracked down the partners and had them killed, secretly, of course. No one was ever able to prove it, but the Blacks knew. Cassiopeia had screamed herself hoarse, and spent three months being treated by a private healer. She had never truly recovered, remaining introverted all through school. People who didn't know better blamed the fact that Marius, her brother, had been a squib, but Cygnus blamed her for all the misfortune on the family. He had even contracted his other daughter Dorea to a Potter because no other pureblood would have her, for fear of squib births.

She knew well the shell her great-aunt had become, and she would never, never, allow that to happen to her son. She had little doubt that Lucius would react badly, and even if he didn't, Abraxas, ever the loyal Death Eater, even after the fall, would do as Cygnus II had done.

Narcissa was a lady. She prided herself on being the essence of a perfect pureblood wife, but in this, in protecting her son and making sure he was happy, Lucius would see ruthlessness that put Bellatrix to shame.

"Asta," she called for her house elf. "Prepare tea. I'm going to have Great-Aunt Cassiopeia over."

Lucius Malfoy came home from a hard day of running numbers for the business. Malfoy Apothecary had taken a hit when he had been accused of being a Death Eater, and even after claiming Imperius and being cleared, the numbers were slow to recover. Thus, it was only years of training that kept him from groaning when he discovered that his wife's spinster great-aunt was at the dinner table when he arrived.

"Hello, Narcissa." he said, offering her a perfunctory kiss on the cheek. "And Cassiopeia, it's lovely to see you again." He nodded to the old biddy with all the charm he could muster. "A pleasant surprise indeed."

"Great-Aunt Cassiopeia and I had some charity things to discuss and our meeting ran long, dear." Narcissa explained. So I invited her to stay for dinner."

"Of course." Lucius said, inclining his head. "So glad that you could stay."

"Thank you, Lucius." Cassiopeia said, in her whispery, papery voice. "Your table is always immaculate."

"It's kind of you to say." Lucius said with a nod. The three talked about non-contentious, easy subjects as etiquette dictated, until dessert had been eaten.

"Lucius, husband, I'm very sorry." Narcissa said, very calmly, putting down her glass.

Lucius's eyebrows went up. "Whatever for, Narcissa?"

"Great-Aunt Cassiopeia is here to get an Unbreakable Vow from you." Narcissa revealed. "I hate that such deception was necessary, but I am quite afraid of your reaction to a discovery I made today."

Lucius's eyebrows climbed upward, and he sat bolt upright in his chair. "I will make no such vow. What nonsense is this, Narcissa?!"

"I'm afraid I must insist, Lucius. Our son has a trine bond and I must protect him, and in order to do so, that means I must protect his bondmates as well."

Lucius's pale face went red, and he slammed his hand down on the table, making the glasses quake and the wine inside them slosh. "No! Absolutely not! I will not have the Malfoy line polluted. Draco will marry a good pureblood girl and carry on the name of Malfoy in proper fashion!"

Narcissa rolled her eyes. "That's impossible. He cannot have a marriage bond or conceive a child with anyone else."

"Then we will have another son!" Lucius said angrily, spitting mad, getting out of his seat and looming over the table. He sneered toward Cassiopeia. "This will be taken care of, one way or another!"

"How?" Narcissa challenged, blue eyes flashing. "You and I both know how that mark on your arm interferes with fertility. There's a reason you have no brothers, that no matter how many wives Nott takes at increasingly young ages, he has only one son. The healer told you that we were lucky to even conceive Draco."

"Healers know nothing!" Lucius blustered, even knowing that she was right. Abraxas had specifically contracted for a Black because of their tendency to breed prolifically, but it had been for naught. The chances of them conceiving again were slim. "And even if it were true, I would still not stand for this!"

Narcissa sighed as if she was greatly disappointed in him, the picture of calm. "Then I shall greatly miss you, Lucius. I will, of course, remain a widow and care for our son, at least until he reaches school age. I owe you, and our son's House that much."

"Your friend Belinda throws a lovely funeral, Narcissa. I'm sure that she could help you with all those unfortunate details." Cassiopeia murmured. "I would be more than willing to move in and assist you with Draco."

"Thank you, Aunt Cassiopeia." Narcissa said, with a beatific smile.

"What do you plan to do, Narcissa?" Lucius scoffed. "Cast the killing curse? I don't think you have it in you to hate me that much."

Narcissa picked up her wine. "Nothing so gauche, my love. I certainly wouldn't want to risk Azkaban or bring the Aurors to my door and traumatise our son. No, it's already done. Malfoy Superior Red does a sublime job at covering the taste of poison, don't you think?"

Lucius paled and looked down at his wineglass. He hadn't thought anything of Narcissa bringing out Black crystal when her aunt was in attendance. It was the sort of thing that was appropriate to do. Every piece of Malfoy flatware, silver, and crystal had poison detection charms on it. Blacks however, specifically Black women, were known to favour poisons that were passed down from mother to daughter, and because of that eschewed the charms.

"Narcissa," he found himself pleading, even as he headed towards the floo. "You won't do this. I'm your husband."

Narcissa's eyes hardened to chips of blue ice. "You'll find, Lucius, that there is nothing I won't do for my son." She held up a bezoar. "The nanny elf has ensured the floos are locked down, as well as the wards. She cannot let anyone threaten her charge, even the Master of the House. If you want to live, you will take the vow. It is your choice."

"You are cruel, Narcissa." Lucius said, swallowing hard.

"I am a Black." Narcissa reminded him. "You shouldn't be surprised."