Legend of Korra Headcanon

Yakone was originally a healer for the United Forces, secretly using his bloodbending in combination with healing to manage the most grievous wounds before it’s allure began to corrupt him.

Mako and Bolin know they aren’t actually brothers by blood (hence they bend different elements) they just don’t care.

Jeong-Jeong was the first leader of the United Forces Navy.

Before Aang died he traveled to the spirit world and made amends with Wan Shi Tong. In return the spirit returned his library to the world. The ancient knowledge within allowed the four nations to advance so quickly.

Zuko would so be the type to be the best man at Aang and Katara’s wedding reception to give the toast and totally shatter the wine glass with the spoon trying to get the guests’ attention by hitting it and then awkwardly cough and fumble on words trying to say something touching, but it makes little to no sense and everyone except for Aang, Katara, Sokka, Suki, and Toph stare on in confused silence, but they just laugh and roll their eyes and it makes Aang and Katara cry because they know he tried and he loves them and vise versa and he meant well even if he screwed up a majorly important moment in their lives.

After Zuko’s exploits the elite operatives of the United Forces are known as Blue Spirits.

The Sun Warriors eventually came out of hiding and joined with the Fire Nation and began teaching them True Firebending. That is why firebenders are more stable in Korra’s time.

After Tahno’s bending is restored he gives up pro-bending and becomes a member of the White Lotus partially out of gratitude and partially because he felt it was his duty to do more with his gift.

Eventually Azula will let go of her emotional issues and regain her sanity. This loss of anger will also cause her to effectively loose her bending. Despite Zuko’s eventual offer to teach her the Sun Warrior style she declined, finally content with herself.

Toph was pregnant with her second child around the time of Yakone’s trial, but lost the baby after enduring his bloodbending. Sokka was the father that time around.