Avatar: The Last Airbender - The Lost Adventures: Relics
Most of the comics from the Lost Adventures anthology are just cute little oneshots or provide extra details about certain plot points, but Relics felt like it could have been an actual episode, and reveals some crucial (and very sad) information about the history of the airbenders.
It takes place during Book 1, when Aang still has a tiny bit of hope left that other airbenders could have survived by hiding–which actually makes a lot of sense, since the likelihood that every single air nomad (emphasis on nomad) alive would have been in the temples during the Fire Nations attack is incredibly small. He finds a merchant selling airbender relics and claims to have bought them from a mysterious stranger living alone in the mountains.
Aang heads out by himself to investigate and discovers evidence of an air nomad settlement. For a split second he thinks he has found another airbender, that he isn’t actually the last one…
…before the ‘airbender’ turns out to be the merchant to from earlier working with Zhao and his men to lure and trap Aang.
This is sad enough, but Zhao then reveals some truly horrifying information: this was the same kind of trap that Fire Lord Sozin used to secretly continue his genocide of the airbenders.
It turns out that a number of airbenders did avoid the main Fire Nation attack and went into hiding. This was apparently anticipated by Sozin, though, and he managed to lure and kill most, if not all, of the survivors in with similar caches of airbender relics.
Aang manages to escape Zhao, but the comic still ends on a dark note, with him not only accepting that he is the last airbender but also processing yet another atrocity inflicted by the Fire Nation upon his people.
