He had lost her.
She'd gone in to fight Amon, to take him down, and she had lost. Well, she defeated Amon, but he managed to kill her.
Before she'd gone in, she turned to them. "If anything happens to me—"
"It won't," Mako and Bolin both cut her off forcefully.
She eyed them and continued, "If anything happens to me, I want you to find the next Avatar. He'll be an Earthbender. You could train him, Bo," she says, a hint of a glimmer in her eye. "Please, promise me you'll just…look after him for me, alright?"
Once she had agreements from all three, she hugged them all, then turned to leave. At the last second she spun around and kissed Mako full on the lips; shocked, and not wanting to respond because of Asami standing next to him, he tried his best to stand ramrod straight. Breaking away, Korra looked to Asami and softly said, "I'm sorry."
"Korra—" Mako choked out as she walked away, lifting his arm. She gave him one last lingering glance and slowly, he let his arm drop. She walked away.
"Mako," Asami says to him. "Will you stop? They haven't found the next Avatar yet, and even when they do, they won't announce it till he's sixteen."
Aggravated, Mako looks up from his Republic City Times, shakes his head, and says, "Aang was twelve. Korra was four. You don't know."
"Even still, it's only been two years, Mako!" He only ruffles the paper to straighten it and keeps reading. "It's because you still love her, don't you?"
When he doesn't respond, she accuses, "You do! You always did, and now you're hoping to get some sort of sick relationship out of her next life! Well, guess what, it's probably a boy anyway!"
Mako purses his lips and jumps up, flinging the paper aside. "She's dead, Asami! Don't you get that? Dead! Gone! You have no reason to be jealous! She's dead, goddammit!" He pumped a fist, shooting flames into the empty air, then collapsed back into the chair, head in his hands. "She's dead," he repeated, softer this time, more to himself than to Asami.
Asami walked out the door.
A few years later, Mako is traveling the Earth Kingdom looking for her reincarnation. He finally finds the kid in a small village outside Gaoling. Kuru.
"Uh, can I help you with somethin', mister?" the kid asks warily as Mako approaches.
"Yeah, and you gotta deal with it." The kid crosses his arms. The corner of Mako's mouth twitched. It was her.
"I promised someone I'd find you," he says simply.
"Oh yeah? Who?" Kuru challenges.
This time Mako smiles ever so slightly. "Just a girl I used to know," he replies. "Her name was Korra. Maybe you'll get to meet her someday."
"That sounds familiar," Kuru comments.
"Could I talk to your parents?" asks Mako. "If you don't mind."
The six-or-seven-year-old boy takes his hand and begins leading him forward. "Come on, I'll take you to them!"
"Hello, Korra," Mako whispers. "I've missed you."
This is what I do at two in the morning. Actually, now it's almost four because I just can't sleep. It was written out longhand first, then I've just typed it up. When my half-awake brain thought of the "she's dead" part, I had to write it down.
I know both Mako and especially Asami are OOC, but they had to be for this to work. And it was 2 AM. Bear with me.