Slumlife had molded Fii into a wiry thing, both tough and flexible, having grown up dancing through the narrow, dark spaces between buildings, hopping on pipes and swinging from balconies, climbing roofs, and slipping into ducts and crawlspaces to scavenge and run errands for a price. But none of that prepared her for this.

"Edith," she wheezed, gasping for air. "How many more times?" She sounded pathetic, like a wounded dog whining at its owner, and immediately hated herself for it.

But Edith couldn't expect her to do more, right? This was inhumane! Her legs ached and trembled, threatening to collapse under her, and her lungs burned like they were filled with hot coals. She needed rest. And a break!

The seams on the fabric of the bodysuit that Edith had given her earlier began to rip slightly under the stress, the harsh white light of the training room only highlighting the fraying. The advanced, sleek suit, which was supposed to help map and monitor her body, now looked like it had been dragged through a razor field. She could feel the sweat that had saturated the suit start to dry, causing her skin to itch under the clingy, damp fabric.

More sweat trickled down her face, dripping onto the ground in large droplets, and she wiped her brow with the back of her hand, blinking away the stinging perspiration. The fluorescent light overhead cast a harsh glare on everything, hurting her eyes, and she squinted, struggling to see clearly.

"We're almost done," Edith yelled over the sounds of the machines. "Just a little bit more. We need to know your limits." The quack doctor sat behind the observation window in front of a control panel, wearing a lab coat over her usual attire, her glasses looking fogged up, typing furiously on a computer. Sheri sat beside her, looking concerned but calm.

Fii clenched her fist, her nails biting into the flesh of her palm, trying to ground herself in the middle of the disorienting gravitational fluctuations. She felt as if she were being stretched, like a piece of tough leather, pulled in all directions.

She had been ordered to shift her gravity field back and forth rapidly, heavy and light, from her feet to her head and then back again, to test the limits of her power. Each change felt like she was being pushed and pulled by invisible hands, jerking her around and messing with her sense of balance. The back and forth made her stomach lurch and her head spin. It was a horrible experience, and she was sick of it.

Suddenly, the gravitational shift became too overwhelming. Her head buzzed from the vertigo, and black spots clouded her vision. Fii crumpled to the floor in a heap, groaning in agony, her muscles trembling uncontrollably.

"I'm done. I can't do anymore." Her voice came out hoarse and faint, barely audible above the din of machinery. She struggled to prop herself up with her elbows, but her arms buckled and collapsed beneath her, and she fell back down.

Edith's voice crackled through the comm system. "Are you alright?"

"Are your eyes just for decoration?!" Fii shouted back, her frustration boiling over. "Of course, I'm not okay! This sucks!"

"The camera cut out for a second. That's why I asked. Sorry." Edith's voice sounded a little miffed, but mostly concerned. "Helix, pull up the data from her suit sensors. Let's check the readouts on her vitals and the Tidal Force Sensitivity Index."

Edith's talking computer, Helix, began reciting numbers, though Fii was too exhausted to comprehend them.

[Body temperature: 39.6°C, elevated. Heart rate: 191 BPM, elevated. Oxygen saturation: 87%, decreasing. Respiration rate: 32 breaths per minute, elevated. Blood pressure: 184/110 mmHg, elevated.]

It droned on in a mechanical voice, listing her vital statistics.

[Tidal Force Sensitivity Index: 0.89]

Fii didn't know what all those words meant, but it all sounded as bad as she felt. And that final number, whatever it meant, was the highest she had gotten all day. Why did they have to use all that jargon? All she wanted was a simple, "You're fine" or "Yeah, we pushed you too hard."

Edith spoke next, her voice no longer tinged with worry. "You'll be fine. Most of those numbers are pretty high, but for a metahuman, it won't cause any lasting damage." She paused for a moment before adding, "Or in layman's terms, you're a tough kid. A little hard work isn't going to kill you." There was a hint of amusement in her voice.

Fii scowled, wishing she could melt Edith's smug face with a single angry look. She took a deep breath and attempted to sit up once more. This time, she succeeded. Sweat dripped down her forehead and cheeks, rolling off her nose, and she brushed it away with the sleeve of her bodysuit, grimacing in disgust. The effort made her head swim, and she blinked furiously, trying to clear the fuzzy shapes obscuring her vision. "Are you happy now?"

Edith continued, "The important number is the Tidal Force Sensitivity Index; your capacity to endure high tidal forces before experiencing unpleasant symptoms."

"Tidal what-now?" Fii mumbled, still feeling a bit woozy.

Edith cleared her throat and continued in a patient voice. "It's an index we created to measure the tidal forces acting on your body when you manipulate your personal gravity. The Earth's gravity pulls on us, but not uniformly. It pulls harder on the side of us closer to the ground than on the side further away. Normally, this difference is negligible, but the gravitational field you're producing right now is many times more powerful. Essentially, you're creating a localized gravity well centered around your body, but its radius fluctuates as you adjust your personal gravity. And because it fluctuates, its tidal force also varies."

"Speak slum, please?" Fii groaned.

"Hey, if Sheri can understand what I'm saying, then so can you!" Edith snapped, her voice cracking through the speakers, making Fii flinch. "Suck it up, buttercup. You wanted to be a hero, right? Well, heroes don't get to complain when they push themselves too ha—AH! OW—Ow ow ow ow! Shweri shtawp—"

The intercom clicked off, leaving Fii alone in silence once more.

She glanced at the observation window, half expecting to see Sheri throttling Edith. Instead, Sheri was pinching Edith's cheeks and yelling at her while Edith frantically shook her head and held up her hands in surrender, waving them around as if to say she would stop.

Sheri must still be angry at Edith for that experiment last week. Using Sheri to prove that Fii could alter the gravity of others. Fii shuddered involuntarily as she remembered how strange it was to have Sheri floating helplessly above the floor, screaming her head off, calling Edith every curse word that Fii had ever heard, and a few that she hadn't.

At least she didn't blame Fii for it. Edith was the one who coerced her into the test. To be fair, Fii had also been reluctant. The memory of what she did to that guy was still fresh in her mind. She didn't want to hurt Sheri accidentally. But Edith said it'd be okay.

Sheri let go of Edith, who immediately rubbed her cheeks and pouted. Sheri folded her arms across her chest, glaring daggers at Edith before turning around and leaving the room.

Edith picked up the intercom and pressed the switch.

"Okay, let's continue." Her voice still sounded a little nasally and strained, though the annoyance had gone. "It's hard to come up with a simple analogy. Helix, help me out here."

The robotic voice chimed in.

[Have you ever played on a swing before?]

"Yeah, sure," Fii replied, confused. Swings were common in the slums, a place where children gathered to play, make friends, and chase away boredom. She used to spend hours on the one close to her shelter, though the swing was just a repurposed tire, hanging from an old, rusty chain, bolted to the side of a building.

[Then this analogy is sufficient. Think about how it felt when you swung back and forth. At the highest and lowest points, you felt a sort of... tension, correct? Like the world was pulling you back.]

Fii nodded, "Yeah, like I was being stretched out."

[Exactly. Now, when you were at the very top or very bottom of your swing, for a split second, you felt almost weightless, correct? Like you were floating.]

"Yeah, that was the best part," Fii replied with a hint of nostalgia.

[That sensation, that brief moment of weightlessness, is similar to when you balance out your gravitational powers. It's a point where the forces acting on you are momentarily in equilibrium. But here's the thing: while on the swing, even though you felt weightless at the top, the forces acting on you didn't disappear. They were just momentarily balanced. Similarly, when you use your powers, you're playing with forces, balancing them out, but they're always there.]

Fii thought for a moment. "So, when I use my powers, it's like I'm swinging all the time?"

[In a way, yes. But there's more to it. Remember how, when you swung really high and then came rushing down, you felt a strong pull in your stomach? That's because different parts of you were experiencing slightly different forces. Your feet, being closer to the ground, felt the pull of gravity a tiny bit more than your head did.]

Fii's face scrunched up in confusion. "So, you're saying my feet and head were... swinging differently?"

[In a manner of speaking, yes. It's a bit like every part of your body is on its own little swing, and they're all moving slightly out of sync. When you use your powers, especially when you change your gravitational field rapidly, it's like all those little swings are being pushed and pulled in different directions. This difference in how each part of you experiences gravity is what we refer to as 'Tidal Forces'.]

Fii took a moment to process this. "So, when I use my powers, it's like I'm making all those little swings go wild?"

[Precisely. And just like how it can be jarring or even painful if you swing too wildly or get pushed too hard, using your powers too intensely or too quickly can strain your body due to these tidal forces.]

"So, I need to learn to... swing smoothly?"

Edith, who had been silently observing the exchange, chimed in, "That's one way to put it. Your training is about learning to control all those little swings inside you, to make them move in harmony. It's about understanding the forces at play and ensuring they don't pull you apart."

"Okay, I think I get it. It's all about balance and control. Just like when I was on the swing. If I pushed too hard or tried to jump off at the wrong moment, I'd get hurt. But if I swung smoothly, everything felt right."

Fii saw Edith's fist pump from the other side of the observation glass. "Exactly! You get it! You're finally starting to use that big brain of yours." The quack doc chuckled, tapping the glass. "Look at that. Your intelligence quotient went up a whole four points with that one sentence. Who says we can't teach an old dog new tricks?"

Fii glared at Edith. "My age hasn't changed."

"Fine, a young dog," Edith corrected with a shrug. "Close enough."

Fii ignored the jibe. She was getting used to Edith's barbs. The quack doc was often impatient, and she loved to tease Fii whenever she could, but Fii knew it wasn't malicious.

Helix continued.

[And that's where the Tidal Force Sensitivity Index comes in. It's a tool to help monitor and measure the strain on your body as you use your powers. Think of it as a guide, helping you understand your limits and how far you can push yourself.]

"Is the higher the number the worse it is?" Fii asked.

[A TFSI value close to 1 indicates that you are approaching the limits of what your body can handle. A value greater than 1 indicates you exceeding that limit and are at risk of serious injury.]

"So, the higher the better, right?" Fii asked, thinking she understood.

Edith chimed in, "No, the opposite, actually. You want the value as low as possible. Remember, this is a scale to gauge how far you can push yourself, not how much you should exert."

"Right." Fii scratched the top of her head sheepishly. "Sorry, I meant, the lower the better."

"With your current score of 0.89, you are in the yellow zone; you might be pushing yourself beyond what's safe, but the long-term effects will be negligible. But once the value exceeds 0.95, that's when the strain will become detrimental to your health."

Fii frowned, "Why's that?"

"There's a direct correlation between the magnitude of the gravitational alterations and the strain they impose. So, changing your gravity a little causes comparatively less strain, but also less noticeable effects, while dramatic changes result in a proportional increase in the amount of strain exerted on the body, as well as the perceived benefit gained. Ideally, you want to find the sweet spot between the two; small, frequent alterations versus large ones. Over time, the cumulative effect will add up and amplify the benefits gained. This applies to both training and combat."

"Edith. I get it. You're smart, but like I said earlier, slum-speak, please?" Fii huffed in exasperation, flinging her hands up.

Edith rolled her eyes. "Small but frequent changes are good. Big ones are bad." She shrugged, waving her hand dismissively. "But it's not just the size of the changes. How fast you make them matters as well. The faster you alter your gravity, the more strain you'll exert on your body."

"Ugh, this is complicated." Fii groaned, rubbing her temples in an attempt to ease her growing headache. "This is worse than studying for that stupid math test." She stared at her hands. "I wish I could use my power without having to think of all that stuff. Can't I just snap my fingers and—" Fii mimicked a gun firing with her thumb and forefinger, "BANG! The bad guy goes flying?"

Edith scoffed, "Superpowers aren't magic, kid. They have rules, physics, formulas that you have to learn and apply." The quack doctor furrowed her eyebrows and twirled the end of her lab coat between her fingers before continuing. "There are only a very few metas whose powers work in ways that defy those rules, and they're either rare abominations of science or inexplicable manifestations of cosmic power."

"So, no snapping my fingers and watching the bad guy fly into the sky?" Fii sulked in disappointment. "How do you even use this Tidal whatever-thingy in a fight, anyway?"

"We call it Tidal Force," Edith clarified. "Tactically, you'll need to rely on your ability to maintain an optimal balance between increasing your force potential and limiting the Tidal Forces exerted on your body. Once you've honed your skills sufficiently, you won't need to constantly check your TFSI. The process will become reflexive."

Fii exhaled through her teeth, blowing out a raspberry in frustration. "So, basically, practice, practice, and more practice." She wiped her damp hair away from her face and sighed. "As usual."

"Alright, alright. That's enough for now. We'll stop with the tests for today. It's obvious you need a break. Take a bath, eat, and clear your head. Relax and recharge." Edith's voice softened, losing the edge of teasing, and Fii's tension ebbed a bit. "I'll send Sheri in later to give you a massage to help relax those sore muscles of yours. The last thing I want is for you to be laid up with muscle cramps."

Was...was she trying to be nice? Maybe the quack doc was developing a soft spot for her, after all. But she probably shouldn't push her luck. For all she knew, Edith might have something horrible in store for her in the days to follow.

Fii rolled her shoulders, feeling the ache of exhaustion settling in her arms and legs. "What about my training?"

Edith leaned back in her chair and gazed at Fii with a pensive expression. "Take tomorrow off, and rest. I can already tell you're in no condition to practice. Think of tomorrow as a recovery day. Then, the day after that, we'll move on to the next phase of your training."

Wow. Two days off in a row? That had never happened before. Did Sheri have a hand in this? Whatever the reason, she wouldn't look a gift horse in the mouth.

Feeling a bit more reassured, Fii took a deep breath, pushing herself to a sitting position. "Alright then. I guess I'll go wash up." She got to her feet and straightened, wincing as her muscles complained.

She headed towards the exit, only for Edith to speak through the comms once more. "Oh, and Fii? One more thing."

Fii froze, her hand on the door, and turned to stare at Edith.

"Yes?" she asked warily.

"Good work today." Edith smiled, offering her a thumbs-up.

Fii smiled and returned the gesture, before replacing it with a rude one. "There, is that better?"

"Much better," Edith sniggered. "Kids these days."

 

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