The relentless London rain mirrored Callista's mood. Two agonising weeks of gruelling training in the Sanctuary yielded nothing. The Celestial power remained stubbornly out of reach. 

Watcher HQ wasn't a prison, but the sterile halls felt a world away from the vibrant hum of the academy. A part of her yearned for that fragrance-filled haven, the one place she used to dread attending.

Perhaps, she had changed. Once, the world had been a clear picture of black and white — Watchers, good. Vampires, bad. But even their mottos spoke of "strategic elimination," not complete eradication. A nagging truth she'd conveniently ignored for as long as she could remember.

One vampire death, Dmitri had drilled into her, meant a safer world. That simple equation had been her unwavering conviction.

But that conviction felt brittle now, a cracked foundation threatening to crumble. Did she truly need a new belief to unlock this power? Conviction. The cryptic pronouncements of the Celestial echoed maddeningly. Fury surged. She snatched a rock, launching it across the Thames. It skipped a few times before disappearing into the murky depths.

A shadow fell over her. Damien. Black umbrella in hand, worry etched lines on his face usually carved from granite. "Something's bothering you. You know you can talk to me, right?"

Callista met his gaze, a playful nudge with her elbow a shield against the turmoil within. "Don't get all mushy on me, Damien. It clashes with your brooding anti-hero aesthetic."

His eyes narrowed. "Are you pretending everything's fine? The academy...it's changed you."

A sardonic laugh slipped from her. "Change? Isn't that just life?" She sighed, a tremor in her voice betraying her flippancy. "I had a best friend once. Ivan...gone too soon. I thought cleansing the world of vampires would fill this void, ease the guilt. It was my fault he died, right?"

Damien's fingers curled around her arm, his touch unexpectedly gentle. "No, Callie. Without you, more children would have..." His voice trailed off, unable to finish the horrifying thought.

Callista stepped back, her words heavy with feeling. "The lives we lead...the lives we've taken...there's no room for it. A normal life. It seems so easy to blame everything on monsters, but..." She hesitated, then met his gaze with newfound determination. "Adam told me something about Duke Fontaine."

Damien's brow furrowed. "The disgraced Duke of Azura?" A wry smile touched his lips, fleeting and shadowed. "Who knew such a paragon of virtue could be capable of acts far more monstrous than any vampire."

Callista's smirk mirrored his, laced with a hint of bitterness. "And don't think for a second Watcher is all sunshine and rainbows, Damien. You doubt too, don't you?"

His eyes widened momentarily, then softened. "I'd follow you wherever you go, Callie."

"Don't talk like Ivan..." she whispered. A sudden realisation dawned on her, a spark igniting in her eyes. "There's more to this power, Damien. Remember how yours manifested?"

Damien's gaze drifted to the river, a haunted look crossing his face. "It was helplessness...a desperate need to protect."

Callista offered a resolute smile, a touch fragile around the edges. Another rock skipped across the water. Her voice, hardened with resolve but laced with a flicker of vulnerability, cut through the city's monotone. "Let's get back to the Sanctuary. Let's find our true purpose — not just eliminate threats, but protect." Her eyes locked with his, unwavering. "There are people I care about here."

Damien followed her back. A spark of hope kindled in his heart, a delicate light in the mist.

Would she… reciprocate?

Callista and Damien pushed through the throngs of Hunters and Watchers flooding the Watcher headquarters. As they ascended the grand staircase, hushed murmurs followed them.

"Look, it's them..." a whisper rippled through the crowd.

"So pretty," someone muttered under his breath, trying to be discreet.

“Should I ask for her number?”

Damien cleared his throat. He couldn't help but notice how the other Hunters, mostly burly men, seemed to linger on Callista's every move. Her beauty was sharp and striking, a rose amidst a bed of thorns.

Ignoring the whispers, they quickened their pace. Pushing open the familiar door to the Sanctuary, they were met with the hum of celestial energy. A flicker of longing crossed Callista's face.

"Remember when I whooped your ass, mentor?" she teased, a playful jab at their last sparring session.

Damien laughed, a sound seldom heard. "Always eager to relive your victories, are we?" He materialised his heavy blade with a flourish.

"Hold on," Callista interjected, shaking her head. "Hold out your hands."

Damien, surprised, dispelled the blade and extended his palms. "What's this about, Callie?"

"Let's try something new today. Focus your Celestial power on your hands," she instructed. "Light them up."

Damien closed his eyes, drawing upon the wellspring of power within. A soft, white luminescence bloomed in his hands. Callista mirrored the action, then, in an unexpected move, placed her hands over his.

A jolt of energy surged through Damien as their powers intertwined. He felt the raw potential thrumming within Callista, vast and untamed compared to his own.

"Can you feel it?" Callista rasped, her voice tight with exertion. "Like an endless torrent, but I can't seem to grasp it."

Damien squeezed her hand gently. "Don't force it, Callie. Feel. Feel your power, its limits… or perhaps its lack thereof."

With a deep breath, Callista closed her eyes, delving into the vast ocean of power within. It churned like a storm-tossed sea, both exhilarating and terrifying. Tentatively, she reached out with her mind, a tendril of awareness seeking a connection. The power responded, a trickle at first, then a surge that ripped through her like a bolt of lightning.

A gasp escaped her lips as fizzing tendrils of power danced across her skin, setting every nerve ending alight. Her core ached with the raw intensity, threatening to crack under the strain. 

'Protect, my friends, my comrades,' she gritted her teeth, images of Indigo and Damien flashing before her eyes, vivid and desperate.

Deeper she delved, the trickle becoming a torrent. Untamed power roared through her veins, a primal scream threatening to erupt from her throat. Muscles throbbed in rebellion, yet she pressed on, fueled by a fierce determination. 

'Protect,' she groaned, Adam and Natalia flickering at the edge of her consciousness.

‘And my…,’ Callista felt a tremor through her as she pictured a dazzling smile and a pair of smouldering golden eyes — a memory bittersweet and poignant.

Her form ignited, a soft luminescence that pulsed with each frantic heartbeat. The very ground beneath them trembled, dust motes swirling in a miniature maelstrom. Damien breathed her name, a mixture of awe and terror in his voice.

Lost in the maelstrom of power, Callista barely registered him. She could feel it pushing at the boundaries of her control, a wild beast straining against its leash. With a monumental effort of will, she wrestled it in, shaping the chaotic energy with a fierce concentration.

Slowly, the power coalesced, forming familiar shapes in her hands. Her signature blades materialised, but they were different now, pulsing with a kaleidoscope of colours that shifted and danced like living things. The white energy was now shot through with vibrant hues — crimson for her rage, sapphire for her focus, emerald for her resilience, amethyst for her grief — each a facet of her power given form.

"You did it!" Damien exclaimed, awe colouring his voice.

Callista met his gaze, her crimson eyes blazing with newfound confidence, though a tremor still ran through her hands. The light dimmed just as quickly as it flared, the diamond blades returning to their original form. 

"Not just yet," she murmured. "But it's a start!"

******

A tremor ran through the Watcher's Council President chamber. Dmitri, a solitary figure amidst a sea of resignation letters, sat bolt upright. A cruel smile stretched across his lips as a surge of anticipation coursed through him.

The energy signature was unmistakable. Callista. She was on the verge. Soon, the tide would turn. A guttural chuckle, devoid of humour, echoed through the chamber, a chilling harbinger of the coming storm.

The vampires would answer for their transgressions. But Dmitri had a weapon, one he'd moulded through suffering and nurtured with vengeance. A weapon far more potent than they could ever imagine. 

"Eydis," he rasped, his voice laced with a dangerous promise, "your reign is built on ironclad control." He slammed his fist down on the desk, scattering the resignation letters like fallen leaves. "But even iron can break."

The game had changed. Dmitri leaned back in his chair, a predator savouring the anticipation of the hunt. A twisted smile played on his lips as he hummed a dark melody, the lyrics echoing ominously in the chamber.

Iron bars will bend and break

Bend and break, bend and break

Iron bars will bend and break

“My fair vengeance.”