She would protect the world…
Korra was the Avatar. He knew this from day one. He was well aware of the powers granted to the Avatar and how they could bend three extra elements than the rest of the benders in the world. Adding on to that, they were a physical bridge between the two worlds that coexisted alongside each other but never touched. This was what made the Avatar special. This was what made them stand out above the rest and what deemed them as the peacekeeper and savior of their world.
Mako knew all of this from the moment he figured out who she was.
But it wasn't until he actually got to know her and what she was like behind the title that Mako found out what being the Avatar meant.
No room to make any mistakes.
Things he could relate to.
But on a much, much higher scale. One he could never imagine living.
All placed on the shoulders of a developing seventeen-year-old girl.
For the entirety of Mako's life, he taught himself to feel no empathy for others besides his brother. If he didn't care for others, then he would be able to focus on his and Bolin's survival. Living on the streets for the majority of their childhood that was his only and top priority.
That changed with her. Many things did.
To be so young and handed the world to take care of and protect…it couldn't have been easy. Growing up without parents and taking care of his little brother was hard enough. Yet Korra has grown up practically her whole life, knowing that there may come a day where she'd have to sacrifice herself to save the world. She'd been taught to do whatever she had to in order to preserve peace and balance in this world.
They drilled it all into her head, over and over again.
You must protect the world at all costs, Korra. Including your life.
She was supposed to give her life to the world if need be.
But just who would be willing to do the same for her?
Who would protect her at all costs? After all, she was the Avatar. She was the most important person in their world, no exceptions. But only being seventeen, there was but so much she could handle. From what she'd been fed all her life, self-preservation wasn't an option.
So he'd do it.
He'd protect her…so she could protect the world.
If he failed…she failed.
He would never let her fail.
…And he would protect her.