Slumlife had molded Fii into a wiry thing, both tough and flexible, having grown up dang through the narrow, dark spaces between buildings, hopping on pipes and swinging from balies, climbing roofs, and slipping into ducts and crawlspaces to sge 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 colpse 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 uhe 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 itder the gy, damp fabric.

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

  "We're almost done," Edith yelled over the sounds of the maes. "Just a little bit more. We o know your limits." The quack doctor sat behind the observation window in front of a trol panel, wearing a b coat over her usual attire, her gsses looking fogged up, typing furiously on a puter. Sheri sat beside her, looking ed but calm.

  Fii ched 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 dires.

  She had been ordered to shift her gravity field bad forth rapidly, heavy and light, from her feet to her head and then back again, to test the limits of her power. Each ge felt like she was being pushed and pulled by invisible hands, jerking her around and messing with her sense of bahe bad forth made her stomach lurd 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 bck spots clouded her vision. Fii crumpled to the floor in a heap, groaning in agony, her muscles trembling untrolbly.

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

  Edith's voice crackled through the 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 sed. That's why I asked. Sorry." Edith's voice sounded a little miffed, but mostly ed. "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 puter, Helix, begaing numbers, though Fii was tprehend 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 meical 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 , her voio loinged with worry. "You'll be fine. Most of those numbers are pretty high, but for a metahuman, it won't cause any sting damage." She paused for a moment before adding, "Or in yman'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, grimag in disgust. The effort made her head swim, and she blinked furiously, trying to clear the fuzzy shapes obsg her vision. "Are you happy now?"

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

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

  Edith cleared her throat and tinued in a patient voice. "It's an index we created to measure the tidal forces ag on your body when you manipute 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 produg right now is many times more powerful. Essentially, you're creating a localized gravity well tered 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 uand what I'm saying, then so you!" Edith snapped, her voice crag through the speakers, making Fii flinch. "Suck it up, buttercup. You wao be a herht? Well, heroes don't get to pihey push themselves too ha—AH! O ow ow! Shweri shtawp—"

  The inter clicked off, leaving Fii alone in silence more.

  She g the observation window, half expeg to see Sheri throttlih. Instead, Sheri ing 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 st week. Using Sheri to prove that Fii could alter the gravity of others. Fii shuddered involuntarily as she remembered how stra was to have Sheri floating helplessly above the floor, screaming her head off, callih every curse word that Fii had ever heard, and a few that she hadn't.

  At least she didn't bme Fii for it. Edith was the one who coerced her into the test. To be fair, Fii had also beeant. The memory of what she did to that guy was still fresh in her mind. She didn't want to hurt Sheri actally. 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, gring daggers at Edith before turning around and leaving the room.

  Edith picked up the inter and pressed the switch.

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

  The robotic voice chimed in.

  [Have you ever pyed on a swing before?]

  "Yeah, sure," Fii replied, fused. Swings were on in the slums, a pce where children gathered to py, 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 , bolted to the side of a building.

  [Then this analogy is suffit. Think about how it felt when you swung bad forth. At the highest and lowest points, you felt a sort of... tension, correct? Like the world ulling 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 sed, 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 simir to when you ba yravitational powers. It's a point where the forces ag 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 ag on you didn't disappear. They were just momentarily banced. Simirly, when you use your powers, you're pying with forces, bang 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 experieng 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 sched up in fusion. "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 ge yravitational field rapidly, it's like all those little swings are being pushed and pulled in different dires. This differen hoart 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 be jarring or even painful if you swing too wildly et pushed too hard, using your powers too intensely or too quickly strain your body due to these tidal forces.]

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

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

  "Okay, I think I get it. It's all about band trol. 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, everythi right."

  Fii saw Edith's fist pump from the other side of the observation gss. "Exactly! You get it! You're finally starting to use that big brain of yours." The quack doc chuckled, tapping the gss. "Look at that. Your intelligence quotie up a whole four points with that oence. Who says we 't tea old dog ricks?"

  Fii gred at Edith. "My age hasn't ged."

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

  Fii ighe 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 k wasn't malicious.

  Helix tinued.

  [And that's where the Tidal Force Sensitivity Index es 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 uand your limits and how far you push yourself.]

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

  [A TFSI value close to 1 indicates that you are approag the limits of what your body 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 uood.

  Edith chimed in, "No, the opposite, actually. You want the value as loossible. Remember, this is a scale to gauge how far you 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 ohe value exceeds 0.95, that's wherain will bee detrimental to your health."

  Fii frowned, "Why's that?"

  "There's a direct corretioween the magnitude of the gravitational alterations and the strain they impose. So, ging yravity a little causes paratively less strain, but also less noticeable effects, while dramatic ges result in a proportional increase in the amount of straied on the body, as well as the perceived be gained. Ideally, you want to find the sweet spot betweewo; small, frequent alterations versus rge ones. Over time, the cumutive effect will add up and amplify the bes gaihis applies to both training and bat."

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

  "Ugh, this is plicated." Fii groaned, rubbiemples 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. '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, formus that you have to learn and apply." The quack doctor furrowed her eyebrows and twirled the end of her b coat between her fingers before tinuing. "There are only a very few metas whose powers work in ways that defy those rules, and they're either rare abominations of sce or inexplicable maions of ic power."

  "So, no snapping my fingers and watg the bad guy fly into the sky?" Fii sulked in disappoi. "How do you evehis Tidal whatever-thingy in a fight, anyway?"

  "We call it Tidal Force," Edith crified. "Tactically, you'll o rely on your ability to maintain an optimal baween increasing your force potential and limiting the Tidal Forces exerted on your body. Once you've honed your skills suffitly, you won't o stantly check your TFSI. The process will bee 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 fad 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. Rex and recharge." Edith's voice softened, losing the edge of teasing, and Fii's tension ebbed a bit. "I'll send Sheri io give you a massage to help rex those sore muscles of yours. The st thing I want is for you to be id 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 exhaustioling in her arms and legs. "What about my training?"

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

  o 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, wing as her muscles pined.

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

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

  "Yes?" she asked warily.

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

  Fii smiled aurhe gesture, before repg it with a rude ohere, is that better?"

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