~In the Present~

"Excuse me, miss, family only." The paramedic said as Fionna tried to get in the ambulance.
"He's my fiance." She quickly lied.
He hesitantly let her up, and Marshall, who was reclining on a stretcher wearing an oxygen mask, opened one eye. "Hey, Fi? This isn't going to end like the other guy."

"Don't talk." She ordered tearfully.
He grabbed her hand. "I swear, I'm going to marry you."

As she sat outside of the operating theater, Gumball approached her. "Fionna... if Marshall lives..."
"When, not if." She corrected.
"Yes... when... do you want a job at the CIA with us?"
"What's this about?" Fionna asked softly, finally looking away from the red light meaning they were operating.

"You're a good assassin... and let's face it, you two didn't mess up super badly." Gumball admitted. "You two make a wonderful team. Besides, outside of Marshall, you're a valuable asset. And the FBI is just small beans compared to us."
"Isn't he a honeypot?" She asked.

"He was." Gumball admitted. "But now... I think your cover as a... married couple, perhaps? Yes, that would work quite well."
Fionna smiled softly. "Well, he hasn't asked yet."
"Oh, really? 'Cause the paramedics said he did." Gumball shot her a long look.

"Well, they wouldn't have let his 'kind of sort of girlfriend' on the ambulance." She smiled grimly.

"He's not Phoebus."
"I... I know that."
"Do you? It's not you, Fionna. You need to know that. It's this entire line of work. Both Phoebus and Marshall knew the risks when they signed up. But Phoebus' death was quick and painless. And Marshall's going to live. If he doesn't, I'm going to visit his grave everyday to yell at him for interfering in Ms. Rosser's love life."

Fionna smiled briefly, then looked at her friend. Gumball was also staring at the red light, concern etched into his face.
"He's going to live." She repeated.
Gumball looked at her, and smiled softly. "Yeah. And about the job... just think about it, okay? No matter if--" Here he caught himself, staring at the floor as if to reproach it. "Even if Marshall is out of action for a while due to his injuries... that doesn't mean you still can't take the job, with-without him."

"Why?" Fionna asked.
"Because if you die, I don't want to hear about it four weeks later." Gumball told her. "Cake is different, she'd be notified automatically as the next of kin. But you're my friend, and I've attended so many funerals... I don't want to know you died because of an invitation to your funeral. Promise me that much at least."

"Stop thinking about funerals." Fionna stared at the red light, desperate for it to turn off, for Marshall to come out alive. Eventually, it did. Marshall, still unconscious, was wheeled out, while a surgeon approached Fionna. "Is he alright?" She asked immediately.
"Mr. Abadeer should make a full recovery." The doctor agreed. "He'll need to remain here for quite some time, but he will eventually be able to resume his life as it was. Now, Ms. Mertons... if you will kindly return to your own bed..."

"Wait, you two were the ones who ran off, weren't you?" Gumball groaned.
Fionna shrugged sheepishly, and let the next nurse who walked by escort her to her bed.

~2 years into the future~

"Marshall Jr." Fionna's new husband suggested as they buckled their seats for takeoff.
Fionna laughed. "What if it's a girl?"
"Marceline. See? I've got you covered, Fi." Marshall grinned.
Fionna grinned back. "Like you had it covered when you used work as our honeymoon?"

"Fi, do you really think I, a humble government worker, would have been able to afford this alone?" Marshall laughed. "God, I'd give you the world if I could, but if the world's also going to be free, I'll take it."

She leaned forward, wrapping her arms around his neck. "It was a nice honeymoon..."
"I feel like you're about to say 'but'..." He murmured.

She grimaced. "The throwing up and having to execute a drug lord kind of killed the mood..."
He kissed her. "What about the fine dining? The wine? The tier 15?"
"Let it go already!" She giggled.
He kissed her neck. "Never. As long as you are my Fi, it will be tier fifteen. At least I'm not gloating that you fell for my 'corny' pickup lines."

"They are corny."
"Yeah? Well, who fell for them and married me and is carrying my child?" He said pointedly.
She sucked on his lower lip. "Doesn't make those pick-up lines any less awful."
"Mm... I bet you're going to get cravings for my coffee too..." He teased.
"Never!" She protested, descending into a fit of giggles as he tickled her.

They heard a wistful sigh, and stopped, looking across the aisle. Across from them was a little old lady, her hand entwined with her husband's. "To be young and in love again..." She breathed.
"How long have you two been married?" Marshall asked.
"Fifty years." The old man replied. "I remember how it all started like it was yesterday."

The woman rolled her eyes, but smiled anyway.
"Ah, but you don't want to hear that." The old man said. "How did you two meet?"
"We applied for the same job." Fionna explained.
Marshall rested his head on top of hers. "And she was the most beautiful woman I'd ever seen."
"And he told me so with lines like, 'if you were a guitar, I'd pick you'."

"And? Did my amazing musical talent win you over?"
Fionna bit her lip to keep from laughing. "I think it was your sweet side... wait, I forgot, you're a bad boy. You aren't sweet."
He kissed her. "Shhhh. Don't give away my secrets!"

"So you're newlyweds, then?" The old woman asked.
"Newlyweds, best friends, and partners in crime." Fionna listed off.

Marshall kissed her throat, before deciding to deepen it and give her a hickey. She squeaked, and he smiled in a wolfish way.
"Definitely newlyweds." The old man agreed.

"Hmm? No, I hope we're going to be like this forever." Marshall smiled. "Well, the passion might come and go, but the love... that's always going to stay between Fi and I."
Fionna nuzzled him, before returning the hickey. "I love you."
He leaned into her. "I love you too, Fi."