Title: Tithonus

Disclaimers: Entirely not mine.

Author's Notes: For Livia's X-Title Challenge. Tithonus was a Greek youth who fell in love with Eos, goddess of the dawn. Eos convinced Zeus to grant Tithonus immortality, but she forgot to also ask for eternal youth.

Thanks: To shrift for beta and the sheep joke.

"We're not having this fight again."

"Oh, yes, we are." Clark stalked into the study right behind him. If he'd been any more persistent, his teeth would have been embedded in Lex's pant leg.

"Come on, Clark. Haven't we reached the 'agree to disagree" stage yet?"

Clark flashed that disarming smile at him. The smile hadn't changed in twenty years. "Not until you agree with me."

"And we both know that's not going to happen, so why don't we just save the hour we'd waste on this argument and do something better with our time?" Lex lowered himself into his desk chair and winced as his knee popped.

"Because until I understand why you're doing this, I'm not going to let it drop," Clark said.

"What the hell is there to understand? I'm a scientist with money. I fund all kinds of scientific research." Leaning back in his chair, Lex stretched out his legs and tried to look nonchalant.

"And I'm a reporter, Lex. I'm a reporter who lives with you, and I have really good hearing. You've pulled a lot of funding from stuff like cold fusion and other alternative energy, and you've put it all into medicine. I understand the cancer research and the stem cell harvesting and artificial organ development. But cryopreservation? Chelation therapy? Sheep hormones?"

"Since when do you care how I spend my money?"

Clark sighed and ran a hand through his dark hair. "I don't. Really. But this doesn't make much sense to me. You've always been more interested in hard science, not in this crazy alternative stuff."

Lex felt a smile tug at his lips. "Some people might suggest that believing in aliens is pretty crazy."

The mischievous look in Clark's eyes momentarily replaced the worry. "Who says it isn't?" Their eyes met, and the familiar heat and affection flared. Lex was halfway out of his chair before Clark turned away, shaking his head. He sat back down, and the damn knee popped again.

"Look, Clark. I turned forty this year..."

Clark had to be feeling pretty upset, because he whirled around and interrupted. Clark never interrupted. "Is that what this is? Some kind of midlife crisis?"

"No." His sharp tone startled Clark. Startled him too. "It's not a midlife crisis, Clark, because I don't intend to let forty be the middle of my life."

"I didn't realize that was something you had a choice about."

"And I thought you knew me better than that."

No desire in this gaze. This was Clark's searching look, the same one that he leveled at the horizon each night before heading out to patrol. "You've got a personal interest in what you've funded?"

"I turned forty this year," Lex repeated. "I've got a bum knee and a back that hurts if I twist the wrong way. If I had hair, I'd be going gray."

"Lex, everyone goes through that."

Lex did stand up then, headed over to where Clark was standing and slipped a hand behind his head. "You don't."

He watched as realization dawned in Clark's eyes. "Lex..."

"You don't age, Clark, or if you do, it's at a rate we haven't been able to detect yet. For all we know, you're practically immortal."

Clark was shaking his head a little. "Lex, no..."

He gripped Clark harder and looked directly into his eyes. "If you're going to live forever, you are not leaving me behind."

Clark stared at him searchingly, then leaned in and rested his forehead against Lex's. They stood like that for moments, Lex inhaling Clark's sweet scent and curling his fingers into his hair. And when Clark pulled back, Lex could see that he'd conceded.

"Okay," Clark said.

"Okay? Just like that?"

Clark reached out two long fingers and stroked his cheekbone. "I don't want to leave you behind either. Just promise me you won't do anything stupid, like volunteer to be the first test subject for the really experimental sheep hormone project."

"Too late," said Lex. "I meant to tell you, but then things went baaaaad..."

Clark closed his eyes and shook his head, an expression of martyred resignation on his face. "Idiot."

"Your idiot," Lex replied, and kissed his beautiful young mouth.