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Phineas glanced over the side of the sleigh, watching the houses fly past underneath. He'd here before, but it was still cool.
Besides, it wasn't everyday Santa Claus himself asked you to join him on a sleigh ride.
"Phineas."
Hearing his name, Phineas turned to Santa.
"I'm afraid I've brought you out here on false pretenses," he said the words like they weighed on him. Maybe they did, it did sound a bit naughty.
"What do you mean, Santa?"
He didn't reply right away, instead staring out over the heads of his reindeer. "I've been doing this job for a long, long time." Looking at Phineas, his eyes were weary. "I'm tired."
"Gee." Phineas broke eye contact first. "I'm sorry to hear that. Is there something I can to help?"
A small smile tugged at Old Saint Nick's lips. "There is."
Phineas smiled back, ready to agree to help, when Santa spoke again:
"Don't agree just yet. It won't be an agreement you can take back easily."
Smile fading, he blinked. "Okay."
"You covered for me once before--"
"I can cover for you again." When Santa just looked at him, Phineas blushed. "Right. Sorry. Continue."
"You're a good man, never once has your name shown up on my naughty list, except for that one Christmas, you have a kind heart, and a can-do attitude."
Phineas squirmed a little at the compliments, fingers absently playing with the hem of his jacket. "Thanks?"
"I want you to fill in for me, but not for one night."
"I'm... not sure I understand."
Santa sighed. "I want to offer you my job."
Phineas' brow furrowed as he frowned. That wasn't a job, that's who the man next to him was. "But you're Santa Claus."
"And I want to retire, go live somewhere warm. Tropical. Without having to worry about the elves." His eyes brightened at whatever scenic beauty he was imaging. "You'd have everything I have, right down to my magic."
"I honored by the offer, but I don't know if I can." Before Santa could say something, he hurried on, "For one, I don't look anything like you. People would notice."
A jolly laugh left the big man. "The elves are the best cooks you'll ever met, they'd have that fixed by next Christmas."
"I, uh, I didn't mean that."
Santa glanced at him. "It'll take a few years, but the people will grow used to your face instead of mine. Magic will keep them from finding anything odd about it."
For a few moments, Phineas was silent. "How long would I have to do this?"
"Only until you find someone else who can."
"But how long would that take?" He absently looked over the side again, searching out his home of the sea of roofs. They were too far away for him to pick it out. "How often do you find someone like me?"
"Oh, once every few centuries."
Phineas froze. "Centuries?"
"To be perfectly honest," Santa hesitated, "you're the first. That's why this is so important to me."
"You don't know when the next time will be," Phineas whispered. He took a deep breath. "I'm sorry. You're my hero, but I can't do that. I can't be you. I don't like doing the same two days in a row, having to do the same thing every year for centuries..." He couldn't finish. It wasn't just that. His friends, his family, Ferb, he'd have to watch them grow old and die. "Even living that long doesn't appeal to me, not if I have to outlive everyone I know."
"I never said that. Mrs. Claus has been with me since the beginning."
"Okay, so what? I get one person to live centuries with me?" He paused until Santa confirmed it. "I'd have to pick someone, someone else who'd have to go through the same thing." Ferb popped into his head, but as nice as having centuries with his brother sounded, he couldn't do that to him. "I can't."
Santa sighed. His disappointment was palatable, and Phineas wished they weren't so high-up so he could just leave.
"I knew it was unlikely you'd accept, Phineas." Smiling as through the disappointment never existed, Santa looked at him. "Do want to fly around the town again before I bring you home?" There was an almost devious twinkle in his eyes. "I never get to show off just what these reindeer can do."