Tony's agitation that day began with a glass of chlorophyll juice.
"JARVIS, today's blood toxicity reading."
"Thirty-one percent, sir."
JARVIS's voice came from the laboratory ceiling. "At the current rate, it will reach the critical threshold in three weeks."
Tony said nothing. He sat at his workbench, surrounded by more than a dozen holographic screens, each displaying a different element's molecular structure and energy output curve. He had already screened every stable, semistable, and barely usable element on the periodic table. Some simply couldn't withstand the reactor's energy output and melted within three seconds of installation. Some held up, but were even more toxic than palladium. Others neither melted nor were toxic, but their energy conversion efficiency was so low that even getting the armor to stand up was a struggle.
"We've tried every known element?"
"Yes, sir. All one hundred and eighteen elements currently known have been ruled out."
"Then screen them again."
"Sir, the results of another screening will be identical to the last."
"Then do a third."
JARVIS didn't respond again. The element list on the holographic screens began refreshing from the top, data bars flickering row by row. Tony knew this was a waste of processing power, but he needed the numbers on the screens to move. It made him a little less agitated.
That feeling continued to fester over the next few days.
In the lab, he tried adjusting palladium alloy ratios to reduce the toxicity, only to cut the energy output in half. He revised the reactor's power curve four times, and every version triggered red warnings in JARVIS's simulations. Late at night, he sat alone on the living room sofa, staring blankly at the dark ocean beyond the floor-to-ceiling windows, holding a glass of chlorophyll juice that had gone completely cold without taking a single sip. He started having JARVIS play heavy metal at three in the morning, filling the entire basement with sound pressure strong enough to shatter glass. He repeatedly removed and reinstalled the same screw on the Mark III's arm plating, taking it out and putting it back, over and over, until the threads stripped.
Pepper noticed something was wrong with him.
"What's been going on with you lately?" She stood on the glass steps at the laboratory entrance, holding a tablet displaying the latest progress on preparations for the Stark Expo. "You haven't been to the office for three days straight. Hammer Industries was taking more veiled shots at you at another press conference, saying your refusal to hand over the Iron Man Armor technology endangers national security. Do you need me to respond for you?"
The instant Tony heard Pepper's voice, he minimized the reactor diagnostics window, moving as fast as if he were hiding something shameful. By the time he turned around, his face already wore the standard Stark nonchalance.
"Let Justin Hammer talk. His mouth's about the only thing he's got that still works."
Pepper looked at him. Her gaze lingered on his face for a while, perhaps taking in the dark circles that were more pronounced than last week, perhaps watching the way he unconsciously rubbed his chest. But in the end, she asked nothing more. She merely tucked the tablet into the crook of her arm, said, "I'll keep an eye on things at the office. Get some proper rest," and turned to go upstairs.
Tony watched her disappear at the top of the stairs and moved his hand away from his chest. The reactor's blue-white glow shone through his T-shirt onto the back of his hand, also illuminating the fine, twisted dark lines spreading outward from his chest.
His visits to Kamar-Taj grew more frequent.
Sometimes his portal opened straight into the courtyard; sometimes he traced it crookedly with the Sling Ring and opened it right in the middle of the dining hall. Wong had been eating that time, and one look from him was enough for Tony to back out and open another portal himself. He never stayed long. Sometimes he simply vented to Lynn and left when he was done.
"You know what the most fucked-up part is?" Tony leaned against a stone pillar, holding coffee he had brought from New York. He really couldn't get used to Kamar-Taj's tea. "I've tried everything I could. Everything. Not one of them can replace palladium. Platinum melts through the reactor's inner wall in point three seconds. Rhodium's energy curve is an order of magnitude off palladium's. Osmium's even more toxic than palladium. I installed it and ran a blood simulation, and JARVIS slapped a skull symbol on it. Iridium, stable but useless. Cadmium, highly toxic. Zinc, don't make me laugh. One hundred and eighteen elements, all screened, three times. Zero."
Lynn sat across the stone table and set down his teacup. "Then, as for S.H.I.E.L.D..."
"Don't bring up Fury." Tony cut him off, undisguised irritation roiling in his voice. "That one-eyed bastard hasn't shown his face since putting on that little stage play in my living room."
Tony slammed his empty coffee cup down on the stone table and said quietly, "I'm afraid to tell Pepper."
This was what he had really wanted to say tonight. Everything before it had been a lead-in.
"I've already made her CEO. She thinks I'm just worn out from work. She's busy preparing for the Expo every day, and she has to deal with that rabid dog Justin Hammer. I don't want her to have to worry about me too. She doesn't know the truth, but every time she looks at me, that expression like she wants to ask but doesn't dare..."
Tony abruptly fell silent and said no more.
Lynn waited for him to recover a little before speaking.
"Your dad was one of S.H.I.E.L.D.'s founders."
Tony looked up.
"That Homeland-whatever agency. Your father founded it with Peggy Carter, Colonel Phillips, and Nick Fury. He hid something for you in S.H.I.E.L.D.'s old files."
After hearing this, Tony was silent for a while. Then he straightened away from the stone pillar, his lips twisting into a curve that might have been mockery or self-mockery.
"My father? Howard Stark? He was cold. Calculating. He never said he loved me! He never even said he liked me. My clearest childhood memory of him is his back. What did he leave me? Shares in Stark Industries, a pile of old blueprints, and a message passed along through someone else: 'Tony will understand someday.' He wouldn't even tell me to my face. I knew from childhood that his love was always reserved for steel, blueprints, and his country."
Tony pulled the Sling Ring from his pocket and slipped it onto his fingers, his movements a little too forceful.
"If he really left me something, why didn't he give it to me directly? Why hide it in a S.H.I.E.L.D. filing cabinet?"
Lynn didn't argue. Nor did he comfort Tony. He knew that, for someone who hadn't first heard "You are my greatest creation" until his thirties, in a recording of his father, anything he said would be meaningless. He simply waited for Tony to put on the Sling Ring, then spoke.
"Then why don't you just go look? The answer's right there."
Tony stood in the middle of the courtyard. The portal was already open, orange sparks beginning to fly, but he didn't step through immediately.
"You said he left something for me?"
"I said S.H.I.E.L.D. has something he left behind. Whether you go or look is up to you." Lynn picked up his teacup again and leaned against the stone seat, his voice returning to its usual casual drawl.
Tony stood silently for a while, then stepped through the portal.
The portal closed. Only the snowy mountains' night wind remained in the courtyard. Lynn set his teacup on the stone table and leaned back against his chair.
The night wind stirred the prayer flags into a soft rustle. The snowy mountains were silent.