It was a typical gloomy day in the Snape household, the only light coming from the flickering candles that lined the stone walls. Severus Snape was busy brewing potions, a task he found calming.

His wife, Bellatrix Lestrange, was upstairs, heavily pregnant with their second child. Unlike Severus, she found no comfort in the quiet, instead she craved action and chaos.

Suddenly, a shrill scream pierced the quiet. Severus dropped his stirrer, rushing up the stairs two at a time. "Bella!" he called out, worry lacing his voice.

He burst into their bedroom to find Bellatrix clutching her belly, her face pale. "It's time, Severus," she gritted out, her voice strained with pain.

Severus felt a wave of panic wash over him. He hadn't been prepared for their son's birth, and now he had to face the reality of their daughter's arrival.

He quickly summoned a house-elf, instructing it to fetch a healer. As the elf disappeared with a pop, he turned back to Bellatrix, trying to offer comfort.

Minutes turned into hours. The healer arrived and started working on Bellatrix. Severus could do nothing but wait, his nerves frayed.

Finally, after what felt like an eternity, a baby's cry filled the room. Severus' heart pounded in his chest as the healer turned to him, a small bundle in her arms.

"It's a girl," she announced, passing the baby to him. Severus took his daughter into his arms, her wailing subsiding as she sensed his presence.

He looked at her, her tiny face a perfect blend of him and Bellatrix. His heart swelled with love and fear, his thoughts in a whirl.

"Have you thought of a name?" the healer asked, breaking his reverie. Severus looked at Bellatrix, who was watching them with a tired smile.

"Eileen," he said softly, "after my mother." Bellatrix nodded, reaching out to touch their daughter's soft cheek. "Eileen Lestrange-Snape," she whispered.

The following days were a blur of sleepless nights and endless nappies. Severus found himself constantly worrying about Eileen, his fears heightened by his lack of experience.

He found solace in his potions lab, brewing concoctions to aid Bellatrix in her recovery and Eileen in her growth. The familiar routine gave him a semblance of control.

Yet, despite the chaos, moments of peace were found. Late at night, when Eileen was finally asleep, he would watch her, his heart filled with love.

Bellatrix too, was different. The wild energy that usually surrounded her had mellowed, replaced with a quiet determination to be a good mother to their children.

Slowly, Severus found himself adjusting to his new role. Each day brought new challenges, but also new joys. His daughter's giggles became his favorite sound.

He learned to decipher her cries, to soothe her when she was upset, to make her laugh. He found a new purpose in being a father.

Bellatrix watched him with amusement, her eyes sparkling with love. "You're a natural, Severus," she teased one day, her voice filled with pride.

He merely grumbled in response, but his heart warmed at her words. He was far from perfect, but he was trying, for his family.

As weeks turned into months, Severus found a rhythm. He was still learning, still making mistakes, but he was no longer unprepared. He was a father.

And as he watched his daughter grow, his heart filled with an immeasurable love. A love that gave him strength, a love that made him brave.

He was Severus Snape, a potions master, a spy, a husband. But above all, he was a father to a beautiful girl named Eileen.

And as he held Eileen in his arms, her tiny hand grasping his finger, he knew he wouldn't trade this for anything in the world.

For in the end, it wasn't the potions or the magic that mattered. It was love, love for his wife and his children. And that was something he was prepared for.

So, he held his daughter closer, whispering promises of love and protection. Promises he intended to keep, no matter what the future held.

And as he rocked Eileen to sleep, he realized that he was not only a father. He was a protector, a guide, a source of comfort.

He smiled at the thought, his heart filled with a newfound determination. He might not have been prepared for his daughter's birth, but he would be prepared for everything else.

Because that's what being a father meant. It was about learning, adapting, and always being there for his children. And Severus Snape was ready for it.

And so, in the quiet of their home, surrounded by the love of his family, Severus Snape found his true calling. He was a father, and he was prepared.

He held Eileen closer, whispering words of love into her tiny ear. "I'm here, Eileen," he said softly, "And I always will be."

And with that promise, he found a peace he hadn't known before. A peace that came from being a father, a peace that came from love.

And so, despite being unprepared for his daughter's birth, Severus Snape found himself ready for the journey of fatherhood. A journey filled with love, joy, and the occasional potion mishap.

But no matter what came his way, he knew he would face it head on. For his family, for Bellatrix, for Eileen. For love.

And so, Severus Snape, the unprepared father, became the most prepared man in the world. For love had prepared him for everything.