So Korra looks a lot like Noatak. She looks, basically, like genderbent Noatak. If Noatak had a twin sister, she would have looked a lot like Korra. If Noatak had a daughter…
What if, for a brief amount of time - like, after seeing her in the newspapers for the first time - Tarrlok theorized that Korra could be Noatak’s daughter? As so many Amorra fanfic authors have noticed, Korra and Noatak share not only physical characteristics, but emotional ones, like their courage, strong convictions and willingness to stand up for their beliefs, stubbornness, and passion in what they believe in. Korra is also a powerful waterbender, like Noatak. Remember, the last time Tarrlok saw his older brother was when he ran away in the middle of the tundra, to start a new life. The way Tarrlok initially thought about it was that it couldn’t have been totally impossible - the idea of Noatak running away and catching a ship to the Southern Water tribe, to start over. He might have changed his name, and once he was older, chosen to settle down and marry a woman who had grown up there.
And then, boom, then came Korra.
Tarrlok is unable to shake this disconcerting feeling, and it piles on top of all the other complicated feelings he has for this girl: the reincarnation of the man who had made Yakone the abusive parent he was; the person who he and his brother had been raised to destroy; the person who he’s planning to make his ally in the critically important fight against Amon and the Equalists. He goes to the Republic City archival library and searches for old newspaper articles that came out around the time that the Order of the White Lotus confirmed that Korra was the Avatar, trying to find something, anything, that would confirm or deny his suspicions.
He finally comes across a small, grainy, black-and-white newspaper photo of the very young Avatar with her parents and waterbending teacher, Master Katara. He notices that her father’s name is Tonraq, but that doesn’t mean anything, Noatak could have randomly chosen it—
He studies the photograph for a long time, focusing on what he can see of Tonraq’s face, straining to see any resemblance to the brother he remembered from so long ago. Nothing stands out to him particularly, but he wonders if Noatak had surgically changed his appearance, like Yakone had.
Tarrlok rules it out after a while. Yakone had money, power, and connections; fifteen-year-old Noatak had nothing but the clothes on his back.
So he is forced to conclude that his suspicions had been unfounded. Korra is not Noatak’s daughter, his niece. She’s just Korra, the daughter of two anonymous waterbenders from the South Pole. He’s relieved on one level - all things considered, it would complicate things even further to have the Avatar be his niece as well. He couldn’t in all good conscience allow her to be on his task force, or allow her to face Amon at all, if that were the case.
Still, though, Tarrlok can’t shake the feeling of disappointment that makes his chest ache, and he doesn’t realize just how badly, how terribly, he had wanted it to be true until it’s clear that it isn’t. He has no proof that Noatak made it out of the tundra that night and is is alive and well in the South Pole, happily married, and the proud father of a talented daughter. The Avatar, that strong, tough girl with an aggressive attitude that mirrored his own so perfectly, isn’t his niece after all.
And as Tarrlok puts the newspaper clippings away and leaves the library, he is reminded, once again, that he has no family left.