I actually wrote this fic quite a while ago, but had to wait to post it anywhere until it had been posted to the valyrian_forged community on LJ. It's "dedicated" to the members of the LJ Westerosorting comm who voted for me as Tyene Sand in the character meme last year :)

Her father was half a mystery to her; gone more often than he was present.

Yet when he visited, their days together were golden ones, the time more precious for the fact that there was so little of it.

Tyene wanted more than anything to please him, yet what little remained in her memory of her mother kept her from being as sensual and adventurous as he.

The poisons, however, were an altogether different story.

She'd heard all her life of her father's intelligence, and she'd known for some time that he loved potions and poisons as much as he loved women and good Dornish wine. She may not understand so very much of what he loved, may not be interested in so many of those things...but poisons...the very idea of them sent a thrill through her.

Yet it was many, many years before she told him as much. She was almost frightened to do so, at first. She was the innocent one, after all - the child of one of the most forbidden loves Oberyn Martell had ever entertained, and quiet and sweet on top of that. She was no Obara, fierce and spear wielding; she was no Nymeria, a Dornish beauty who tucked daggers in the most unlikely of places. She assumed that she was just Tyene, "warm and golden as the southern sun", her father called her.

But the southern sun can also be hot, unyielding, and treacherous, Tyene mused.

And finally one day she asked him to teach her what he knew of the poisons he loved so much. She'd half expected him to refuse, though later she never understood how she thought he would or could do so. Instead he'd smiled - a fierce, closed-lipped grimace of sorts - and said, "Ah, so this will be your independence."

He had taught her everything - how to make the vile mixtures, which ones were best dissolved in other liquids and which would do for making a blade - any blade - more dangerous than it already was. Tyene had expected to feel some trepidation in regards to learning such a dark art, but when she searched herself she found no such feeling.

Perhaps it was because as he showed her the art of poisons, her father told her stories of the sister he'd loved and lost. Though she understood that Elia Martell had been killed - and that Oberyn Martell meant to do something about it, someday, at least - it wasn't until later that Tyene knew the extent of what her aunt had suffered. She had to bite back the anger that rose in the back of her throat like bile, the day that her cousin Arianne almost casually revealed the entire story. Soon after this her father returned to Sunspear for another visit, and having been on a long trip to Essos and the Summer Islands he had plenty of new information to share with her. Tyene could feel her face burning with the anger that had barely dissipated at all since hearing the full tale of Elia's death, and she twisted it up in frustration as she ground and mixed the ingredients as her father bid her to do.

Not a little time had passed when Tyene suddenly felt her father's gentle hand, calloused from the spear he wielded so deftly, take hold of her chin and turn her face toward him. "What is wrong, my daughter, my fair, sweet girl?"

Tyene did not want to tattle on Arianne, but she found herself admitting that she now knew what had happened to her aunt, Elia. All of what had happened, exactly what had happened. Something like sadness passed over Oberyn's face as she explained herself, though he hid the feeling quickly and made the comforting gesture of tucking her hair behind her ears before cupping his hands over her cheeks. Tyene immediately felt better, calmer...her father always had such an effect on her. "Don't you want...revenge?" she asked softly. Truth be told, she already knew the answer - but she wanted to hear him say it.

"Every day of my life since I was told that she was dead," Oberyn Martell admitted, his lips curling into a sad smile.

"I want it, too," Tyene whispered, "I who never even knew her."

"And that, my dear, is why you are a Martell." Her father leaned forward and brushed his surprisingly soft lips across her forehead, but when he sat back again he continued to look at her thoughtfully. "You are perfection, Tyene, and you have chosen the ideal interest for yourself, in choosing poisons. Do you want to know why?"

She couldn't help herself; she nodded energetically, though at the same time she wondered how her father always knew exactly what to say to make her feel better - to make her feel happy.

"You are the very picture of innocence." Oberyn moved to pull his hands back, but before he did he gave her chin a soft pinch between thumb and forefinger as he continued in a conspiratorial murmur, "No one will ever suspect you."

Later that evening Tyene was in her room preparing for bed, and she stopped to eye herself in the warped looking glass. The face staring back at her was pretty, yes - not in the ways of her beloved cousin Arianne or her sister Nymeria, and she did not have Obara's strength - and her father was right. She had a childlike innocence about her that she'd never before noticed...or perhaps simply never thought about. She reached up and brushed the tips of her fingers along her cheek. She smiled at herself, but then realized that in doing so she appeared less sweet. In fact, she looked almost...

Treacherous.

Just as the Dornish sun could be.

Tyene quickly wiped the smile off her face and composed it back into a more vacant expression. There. That's better.

Yet she still could not stop thinking about Elia Martell and the horrible things that kind, beautiful young woman had suffered at the hands of the Lannister's monsters.

As Tyene watched her own expression in the looking glass, it was as if a veil was lowered over it.

Someday, she promised herself, someday, I will go to King's Landing.

I will go to King's Landing, and I will poison them all.

Every last one of them.