I made my way through the indoor corridors toward the east wing, keeping to the servant passages when possible.

My muscles protested with each step, but I forced myself to maintain proper posture. Even in these hidden corridors, appearances mattered.

The usual morning bustle felt different. Servants moved with unusual purpose, their paths more direct.

No one lingered to gossip. Guards posted at intersections stood straighter, more alert than normal morning rotation required.

I passed the library entrance, noting Magnus wasn't at his usual post. The Council meeting must have required his presence as well.

Unusual, given his normal reluctance to leave his domain. The air grew noticeably cooler as I approached the east wing's lower and far less attended levels.

Ancient stone walls here predated much of the spire's construction. Their surfaces were worn smooth by generations of passing hands.

The corridor narrowed, forcing me to walk closer to the wall than I preferred. My fingers brushed the stone, feeling the deep cold radiating from within.

The foundations here went deep into the mountain, where natural ice formations had first drawn the Eiskars to build their fortress.

A servant rounded the corner ahead, carrying a stack of formal documents. She nearly dropped them when she saw me, clearly not expecting anyone of rank in these passages.

"Young master," she stammered, pressing herself against the wall to let me pass.

I nodded to the servant as I passed, noting how her eyes darted to the corridor behind me, checking if anyone else was coming.

Down here, away from the usual politics, servants were less guarded in showing their reactions. The passage opened into a broader chamber, its vaulted ceiling disappearing into shadows above.

Ancient columns lined the walls. The air held that distinctive mix of stone, ice, and mineral water that marked the oldest parts of the spire.

Sebastian stood by a heavy wooden door, its metal fittings dark with age. Steam leaked from beneath it, creating an odd fog where it met the chamber's cold air.

"The room is prepared, young master." He gestured to a stack of towels. "You'll need to remove your outer clothing. The process works best with minimal barriers between your skin and the steam."

I shed my formal wear, keeping only the light underthings that training demanded. The cold air bit at my exposed skin, making my muscles clench painfully.

"How long?" I asked, eyeing the door.

"Twenty minutes for the first session. Any longer risks damage to an unprepared body." Sebastian's tone carried that edge of experience I was starting to recognize.

"The heat will be... intense. Your ice magic may react instinctively. You must resist using it to cool yourself."

I nodded, understanding. The point wasn't to endure the heat through magic, but to let it reshape my body's natural limits.

Sebastian opened the door. The ancient door creaked open, releasing a wave of steam that made my skin prickle.

Inside, rough-hewn stone walls disappeared into a hazy ceiling. Wooden benches, darkened by decades of use and moisture, lined three sides of the chamber.

Their surfaces showed deep wear marks where countless bodies had sat before. Iron brackets held ancient lighting crystals, their glow diffused by the thick steam.

In the corner, a stone basin filled with water sat beside a pile of dark rocks, their surfaces etched with long-forgotten runes. Drops of water fell from the low ceiling in a steady rhythm, each one hitting the hot stones with a soft hiss.

The wooden floor planks, smooth from years of bare feet, led to a drain in the center. The air felt thick, almost solid, carrying the scent of heated stone.

Ancient ice magic seals lined the doorframe, designed to contain both heat and steam rather than the cold they usually managed.

This wasn't the polished luxury of the upper spire's bathing chambers. This was something simpler.

"The seals are original," Sebastian said from behind me. "From before the Third Founding, when the family still acknowledged other paths to power."

I stepped inside, feeling the heat press against my skin. The heat hit me hard.

Nothing I'd read about in my past life prepared me for this intensity. Sweat broke out instantly across my skin, running down my back immediately.

"Breathe slowly," Sebastian instructed from the doorway. "Through your nose. The steam will feel thick at first."

He was right. Each breath felt heavy, like drinking air instead of breathing it. My lungs fought against the moisture, wanting to cough.

Sebastian moved to the basin, lifting a wooden ladle. Water splashed across the dark stones, releasing a fresh wave of steam that made my skin tingle painfully.

"Your ice magic will try to protect you," he said, watching my reaction carefully. "You must suppress it. Let the heat do its work."

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He was right again. I could feel my power stirring, responding instinctively to the assault of heat against my body.

Frost tried to form along my arms, but the steam dissolved it instantly. Another ladle of water hit the stones. The temperature climbed higher.

My legs trembled. Sweat ran into my eyes, stinging. The bench beneath me felt like it was burning through my thin clothes.

"Focus on your breathing," Sebastian reminded me. "This is how the body purges its weaknesses."

The heat pressed in from all sides now, making it hard to think. My skin felt like it was trying to crawl away from my bones.

More water hit the stones, and I couldn't stop the small gasp that escaped my lips.

"The heat will build for another few minutes," Sebastian said. "Then plateau. That's when the real work begins."

The heat became unbearable. My lungs seized, and I doubled over as violent coughs wracked my body.

Black phlegm splattered onto the wooden planks, disappearing into the drain below. "That's it," Sebastian said. "Your body is purging the weakness."

Another wave of coughing hit me. More black fluid came up, thicker this time. My skin felt like it was on fire, and dark beads of sweat rolled down my arms.

This wasn't normal sweat - it was almost tar-like, oozing from my pores. I gripped the bench edge as another spasm hit.

Black droplets fell from my face, my chest, everywhere. The heat pressed in, squeezing more of the dark substance from my body.

"Don't fight it," Sebastian instructed. "Let it all come out."

My stomach heaved. More black sludge forced its way up my throat. It tasted like metal and rot, years of accumulated toxins finally being expelled.

The wooden planks beneath me were stained with dark streaks where the corrupted sweat had dripped. My skin felt raw, like it was being scrubbed from the inside out.

Another splash of water on the stones sent steam billowing. I retched again, bringing up more of the black substance. It clung to my lips, stretching in thick strands before breaking away.

Through the haze of steam and pain, I heard Sebastian's good-natured laugh. "You must endure."

I wanted to glare at him, but another wave of black fluid forced its way up my throat. My fingers dug into the wooden bench as my body convulsed.

The heat pressed against my skin like a physical weight, drawing out more of that foul substance with each passing moment.

"This is..." I managed between retches, "...horrible."

"It is effective," Sebastian's voice held no sympathy. "Your body has accumulated years of waste. This is one way to get stronger faster."

Another splash of water hit the stones. The steam thickened, and I felt fresh beads of that dark sweat forming across my skin.

My stomach clenched again, bringing up another mouthful of the metallic-tasting sludge. The wooden planks beneath me were becoming covered in dark stains, each drop of corrupted sweat marking another piece of weakness leaving my body.

The drain in the center gurgled softly, carrying away years of accumulated toxins. "You must endure," Sebastian repeated, his tone still carrying that hint of amusement.

"The process cannot be rushed or shortened. Each drop of that black fluid is poison leaving your system."

Through the haze of steam and black sweat, I managed to lift my head. "Is it... twenty minutes yet?"

My voice came out ragged, each word fighting through the thick air. "Just how hot is it in here?"

Sebastian tilted his head, and even through my blurred vision, I could tell he was trying not to smile. "I lied. Twenty minutes was quite some time ago. You can handle more."

The admission should have angered me. Instead, I found myself choking out a laugh that turned into another bout of coughing up black fluid.

Of course he'd lied. The Sebastian I thought I knew would never have dared such deception. But this Sebastian, the one who'd survived the southern borders, who carried burn scars beneath his perfect collar, he was teaching me the way he'd learned.

The heat pressed in, impossibly more intense than before. My skin felt raw, like it was being scraped from the inside out.

Another splash of water hit the stones, and fresh waves of that tar-like sweat oozed from my pores.

"How much longer?" I managed between gasps.

Sebastian's answer was lost in another wave of coughing. More black fluid splattered onto the wooden planks, joining the growing stains below.

The heat drew out toxins I hadn't known existed in my body. Through the steam, I saw Sebastian move to check the ancient seals around the doorframe.

The stones hissed as Sebastian added more water. Steam billowed up, making the ancient lighting crystals seem even dimmer.

My vision blurred as fresh sweat ran into my eyes, but this time it was clearer, less dark.

"The black is almost gone," Sebastian noted, his tone carrying a hint of approval. "Your body is adapting faster than expected."

I gripped the bench edge as another spasm hit, but less of that foul substance came up. The metallic taste in my mouth was fading.

"That'll do," Sebastian said, "Let's get you cleaned up."

I tried to stand, but my legs buckled. Sebastian caught my arm before I could fall, his grip precise, supporting without appearing to do so.

"Careful now. Your body needs time to adjust."

He guided me to a separate chamber where cool, clean air brushed against my raw skin. The sensation was almost painful after the intense heat.

A stone basin filled with clear water waited, wisps of steam rising from its surface. "The water is treated with minerals," Sebastian explained, helping me sit on a wooden stool.

"It will help close your pores properly." He poured a ladle of the water over my shoulders.

The liquid felt different - somehow thicker than normal water, leaving a tingling sensation wherever it touched. My skin practically hummed as the minerals worked their way into newly opened pores.

Sebastian worked methodically, each pour of water targeting specific muscle groups. The mineral-rich liquid washed away the last traces of black residue, revealing skin that felt newer somehow.

Raw, but stronger. "Your body will be sensitive for several hours," Sebastian said, finishing the rinse.

"Avoid cold for the rest of the day. No ice magic until tomorrow morning." He handed me a soft towel, its fabric notably different from the usual household linens.

I patted my skin dry with the special towel, my mind turning to my scheduled training. "What about Lady Brunhilde? Even with the emergency Council session—"

The door burst open, letting in a blast of cold air.

"And what exactly do you think you're doing with my student?" Lady Brunhilde's voice carried its usual edge of impending violence.

Sebastian didn't even turn around. "Helping him build a proper foundation. The kind you'd approve of, old friend."

Her stern expression cracked, a rare smile breaking through. "Ha! I wondered how long you'd wait before dragging him down to your torture chamber."

She strode in, examining my reddened skin with an expert eye. "Black sweat's already clearing. Good. The boy's adapting faster than expected."

I looked between them, pieces clicking into place. "You knew about this?"

"Of course I knew." Lady Brunhilde snorted. "Who do you think showed Sebastian these methods in the first place? Back when he was stationed on the southern border with my unit."

Sebastian's lips twitched. "As I recall, you were considerably less gentle with your instruction."

"You survived, didn't you?" She clapped him on the shoulder with enough force to stagger a lesser man. Sebastian didn't even sway.

The casual display of familiarity struck me. This wasn't the formal respect of servant to noble. This was the easy comfort of old comrades who'd faced combat together.

"Though I must say," Lady Brunhilde continued, "your technique has improved since those days. Getting soft in your old age?"

"Merely adapting to the student's needs." Sebastian's tone carried that same dry humor I'd heard earlier. "Not everyone requires your... direct approach."