I think if there's gonna be a 'The Firelady' then we'll see Ursas and Irohs story. (duh).

But there probably is a LOT of speculation of how this could be going....

This is my version, with some sidenotes:

WARNING: POTENTIAL SPOILER! (spoilertag didn't work; HTML not well-formed....dang)

Both Ursa and her sister have been raised for a long while on Ember Island or some other FN island, where they get to hear of their grandfather being Roku, at the age of 18 they are contacted by The White Lotus, the secret organisation their grandmother has set up, with the goal of ending the war and help the avatar to recreate balance. The White Lotus heard from informative sources the Royal family, the Firelord and his two sons, where about to get a beachhouse near the location Ursa and her sister live. The OWL comes with a plan in which one of the two sisters should marry the Firelords oldest son, with as a result bring offspring that will reunite the family of Roku and the family of Sozin.This offspring should help end the war according to the informative source of the Firemages, who during that time stillcooperate withRokus offspring and OWL.In a festivity at the Royal beachhouse the two sisters should be invited and wooed by the Firelords two sons. Ursas older sister is lucky; Iroh falls in love with her, seems like true love. Also Ozai finds himself flirting with Ursa.

Mainplan is now for the oldest sister to marry Iroh, which happens, and she gives birth to Lu Ten. Irohstillknows nothing about OWL. The older sister could have died while giving birth, making Iroh the only parent left to take care of Lu Ten. Lu Ten at this point is the one destined to become future Firelord to help restore balance to the world, without Iroh knowing it.

Meanwhile Ursa has gotten married to Ozai and has given birth to two children; Zuko and Azula. Until the childrens birth, Ozai used to be a nice man, but throughout the years he turns bittered and jealous of his brother. Ozai wants to be the next Firelord, and Ursa realizes.

Iroh is away from home a lot. During different sieges Iroh shows himself a strong man. Iroh, being the future firelord himself, is a willing man. He has been raised by Firenation propaganda and always has tried to stick to the ideals of FN, but during diversing sieges he realizes how rough things are going. Innocent women killed, prisoners taken. For a long while Iroh plays the part of the more righteous general, but doubt has entered his mind. Around the time Lu Ten is grown up and ready to fight in the FN army alongside his uncle uncle still is a fanatic fighter for his country, but all is about to change.

OWL is willing to do everything to protect Lu Ten, for he should be the Firelord who will help the avatar to bring back balance to the world. Unfortunately, there's a leak. Until now the OWL has had a strong connection with the Firesages, but a big part is too much under threat of Firelord Azulon...they get scared and a gigantic part decides to turn against the OWL. The Firesages decide to do everything to stop Lu Ten from becoming the future Firelord after Iroh. They find their way to bribe soldiers in the army, to make a plot to put Lu Ten in the frontline of the army, and no other soldier will try to protect him. Iroh meanwhile realizes something's wrong, but by that time it's too late. Lu Ten was the first to be killed.

Ursa hears about this. Desperately she communicates with the OWL; it's time for plan B; the only eldest child left who has both Roku as Sozin as ancestors is Zuko. Since Ursa knows about Ozais frustrations of not becoming Firelord, she decides to approach him to come up with a plan. Despite of that Ursa feels guilty of not letting Iroh know of what is going on.

Plans are getting out of hand though, Azulon rejects and is now even planning to kill Zuko....(maybe very maybe by some influence of the Firesages who know about OWL's plans?). Ursa now not only feels threatened of not executing the OWL's plans, but she feels threatened to lose her own son; she contacts the OWL to help her forge Azulons will and ....'end' him.

Ozai decides to banish Ursa....(this is the part I find the most confusing, I'm clueless why he does this) he might distrust Ursa after all that happened. Maybe he found out about Ursa being Rokus offspring? THOUGH without knowing about Zuko being seen by the OWL as the destined Firelord to help the avatar end the war?

Iroh returns home from the war that night, just after Azulon has been killed. He feels confused, sad, defeated...and his angst only gets worse when he is witness of Azulons death. I think that night, when Ursa is about to be banished, Iroh gets to hearabout the OWL, begging Ursa what is going on. Iroh will be in some kind of impassefor a while, before deciding to join the OWL.

Ursa decides to retreat somewhere, until the moment she hears of Zukos Agni Kai with his own father and being banished in about a few days. She decides to try to find where he is, and tries to contact the OWL, who might be able toarrange a meeting between Zuko and her. Unfortunately, she decides to go to the traitors within OWL; the Firesages.....Ursa is getting captured by them and put in a jail on a remote island. Meanwhile Iroh, who found out about Zukos banishment, tries to contact Ursa, but Ursa seems disappeared. Iroh decides to promise himself to guide Zuko during his banishment, to eventually help him until he finds Ursa.

The OWL finds out about the Firesages being the traitors, and finds out where Ursa is being captured. They try to release her, but after they do they find out Ursa has gotten very ill from a broken heart aswell as germs (lol) and it's too late to save her. Ursa while dying begs the members of the OWL to get to Iroh and ask him to take good care of her son, and guide him to 'his destiny'. [/spoiler]

This is just a vague theory, because actually the whole Firenation story thingy is confusing me .