William swam up from unconsciousness into a world constructed entirely of dull, throbbing pain. Every muscle fibre screamed in protest, a deep, pervasive soreness that felt less like exercise fatigue and more like he'd been systematically tenderized. "Feels like I've been hit by a rhino or something. Note to self," he thought groggily, consciousness flickering like a faulty monitor, "query local ecosystem for creatures large enough to use humanoids as tackling dummies. Add to 'Avoid At All Costs' database." Breathing felt like a chore; even shifting his weight slightly sent waves of aching misery through his limbs. All physical parameters reporting significant discomfort levels. Probable cause: Cascading physiological shock.
The second sensation, cutting through the pain, was warmth. A gentle, steady heat radiating from nearby. He managed to pry leaden eyelids open, blinking against the dim, grey light filtering into the cave. Julia sat beside his bedroll, her back straight against a moss-covered log, watching him. Her eyes were shadowed, underscored by dark circles that spoke of a sleepless, worried night, her usually vibrant features drawn and pale. But the moment his eyes flickered open and focused, he saw the tension visibly drain from her shoulders. A single, errant tear traced a path down her cheek before she hastily wiped it away. She offered him a weak smile, fragile but genuine.
"William," she breathed, her voice hoarse with fatigue and relief. "You're awake. Finally. How… how do you feel?"
He attempted to push himself up onto his elbows and immediately regretted it. A sharp, coordinated protest flared through his entire body, forcing him back down with an involuntary groan. "Like… like I wrestled a bear and lost," he managed, his own voice raspy, throat dry. "Feels like every muscle fiber filed a formal complaint. What… happened?"
Julia's smile faded, replaced by a serious, almost apologetic expression. "You fainted, William. Collapsed completely. Late last night. We heard a thud from near the edge of camp and found you unconscious." She leaned closer, lowering her voice slightly. "Edward carried you back. We checked thoroughly for injuries, bites, breaks, anything, but found nothing new. Your breathing was shallow, though, your skin cold and clammy, and… there was a faint bluish tinge around your lips for a while." Her brow furrowed deeply with remembered worry. "Honestly, William, the symptoms looked alarmingly like moderate mana backlash, but… we know you are still not quite at the stage of casting the Light spell successfully yet. We were deeply worried it might be something else entirely, perhaps a delayed reaction to the goblin bite, some forest sickness we don't know… Edward and I agreed I'd watch over you closely through the night while he kept guard. We couldn't risk moving you in that state, not knowing the cause."
William's mind, sluggishly rebooting through the fog of pain and exhaustion, pieced it together. The Light spell success. The impossible heat map. The bar chart. The exhilarating feeling of the data interface… then the dizziness, the dimming lights, the crash. He'd pushed way too hard, dazzled by the discovery, completely ignoring the energy cost of running that… whatever it was. "Classic rookie mistake," he berated himself. "Overconfidence bias leading to catastrophic resource mismanagement. Exceeded system limits without implementing basic monitoring or failsafes." He felt a flush of sheepishness, knowing his explanation would be incomplete but necessary.
"I… I think I know what it was," he admitted, carefully keeping his gaze lowered, focusing only on the part they could understand. "Last night… I tried the Light spell again. And… it finally worked." He allowed a touch of the genuine remembered wonder into his voice. "But right after… things felt… strange. Really lightheaded. Dizzy. The light from the stone flickered… and that's it. That's the last thing I remember." He deliberately omitted the visual interface, the mental commands, the true likely cause of his system overload. Explaining linear regression analysis or UI design principles as a form of magic seems… unlikely to be well-received. Decision: Maintain information compartmentalization.
Julia's face lit up at his words, pure, uncomplicated relief flooding her features first, immediately followed by dawning comprehension connecting his success to his collapse. "You did it! You cast the Light spell!" Her initial joy was palpable. "Oh, William, that's wonderful news! All that persistence…" She reached out instinctively, squeezing his hand warmly. Then, just as quickly, her expression sobered again, the pieces clicking into place. "But the collapse… the symptoms… that explains it. William," her tone became serious, cautionary, "you need to be more careful! What you experienced was mana backlash, almost certainly triggered by pushing too hard right after your very first success. It is not something to be taken lightly."
She explained, in detail, the dangers of overexertion. "Your body has a natural mana capacity, a limit…" she explained, perhaps recalling his earlier difficulty with analogies. "And your ability to absorb ambient mana is like the spring that feeds it. If you draw water slowly, the spring keeps the well mostly full. But if you try to drain the well too quickly with powerful magic…" she made a rapid scooping motion, "…you empty it faster than the spring can replenish. Your body then tries to compensate, desperately pulling in ambient energy too fast, too forcefully. That uncontrolled influx is the backlash. It floods your system, strains your pathways."
She sketched a quick diagram in the dirt beside his bedroll, a circle (the well), an arrow going out (use), a smaller arrow coming in (replenishment). "In mild cases, like yours seems to be, thankfully," she continued, tapping the drawing, "it results in deep exhaustion, muscle pain like you're feeling now, dizziness, sometimes nausea. And then you faint, essentially. But severe backlash…" her voice dropped, her eyes holding a stark warning, "can cause lasting harm. It can scorch your ability to channel mana, leaving you magically crippled. It can damage your nerves, your organs… your very life force. There are cautionary tales whispered in the Guild halls, William, powerful mages, consumed by ambition or desperation in battle, who pushed far beyond their limits and literally burned themselves out from the inside."
William listened, the earlier giddiness completely extinguished, replaced by a cold knot of apprehension. He hadn't just been playing with a cool mental interface. He'd been redlining an unknown, potentially lethal power source without any safety protocols. The danger wasn't just external threats anymore. It was potentially internal, self-inflicted. Error handling analysis: Catastrophically inadequate. Need to establish safe operating parameters immediately.
"I… I understand," he said, his voice subdued, genuine this time. The memory of the debilitating exhaustion, the moments before blacking out, felt far more ominous now. "That was… foolish. Reckless. I'll be more careful. I promise."
Just then, Edward ducked back into the cave, moving silently despite his size and gear. His expression held a faint trace of relief as he saw William conscious. He'd obviously been keeping close watch from just outside.
"Awake," he stated, less a question, more an observation. His gaze was sharp, assessing. "Good. Overheard Julia. You cast the Light." A flicker of something, "impressed surprise?", crossed his face before settling back into neutral. "Impressive speed for a novice. Also," his voice turned stern, "profoundly foolish to push yourself to collapse." He crouched down near the fire pit. "Listen to Julia, William. Mana backlash isn't some minor inconvenience. Saw a promising shield-mage in the Western Marches try to hold a barrier too large against an ogre charge once. Held for five seconds, then just… dropped. Burned out from the inside, they said. Didn't get back up." He fixed William with a hard stare. "Magic demands respect. Respect your limits, or they will break you."
William nodded again, feeling a flush of shame under Edward's stern gaze, mixed with gratitude for their care. He'd been arrogant, caught up in the excitement, treating mana like an infinite resource on a debug server instead of a fundamental, potentially dangerous biological energy. "With great power comes great responsibility," he thought, the old comic book adage suddenly feeling intensely relevant. "Except in my case, it's more like 'With barely understood, possibly unique power comes the urgent need for rigorous safety testing and resource monitoring to avoid accidentally frying one's own nervous system'."
"I'm sorry," he said again, meeting both their gazes as sincerely as he could manage through the aches. "Truly. I got carried away. The excitement… I wasn't thinking about limits. It won't happen again."
And he meant it. But even as the apology left his lips, a separate partition in his mind was already running calculations. The backlash was a critical data point. It confirmed the 'Data System' used his mana, and used it voraciously. He couldn't abandon exploring it, the potential was too immense. But he had to find a way to monitor his reserves, to understand the cost of different visualizations or queries. Objective: Develop internal mana-monitoring protocol using Data System interface itself? Create real-time feedback loop to prevent future resource exhaustion. A debugger for his own magic. The irony wasn't lost on him. He still couldn't risk telling Julia and Edward, not yet. Trying to explain modern statistics and data analysis and how it has been combined as a form of magic, they would likely think he hit his head somewhere and wasn't thinking right. But the possibilities… applying data analysis to magic, through magic…
He pushed those thoughts firmly into a background process. Priority one: Recover. Priority two: Reach the capital. Priority three: Learn the conventional magic Julia could teach him, carefully, respecting the limits. And Priority four, running silent in the background: Cautiously, meticulously, begin reverse-engineering the most fascinating, powerful, and dangerous system he'd ever encountered, himself.