After rewatching the entire Season 1 and all the episodes available for Season 2, one question always stays in my mind.?? A quick cut and paste from Wikipedia gives some info on what we learned about Zuko's mom:

"Shortly after the death of Iroh's son, Lu Ten, her husband Ozai asked his father, the Fire Lord Azulon, to pass Iroh's birthright to the throne to him. Ozai considered Iroh an unworthy quitter who let the death of his son get in his way of conquering Ba Sing Se. This dishonorable request only infuriated Azulon, who declared that Ozai would be fittingly punished for venturing to betray his own brother in his time of sadness. It is unknown what exactly this punishment was or if it was even carried out, though Azula told Zuko that it was to have him killed so that Ozai knew how it felt to lose his own first-born son. By the next morning, Ursa had disappeared, Azulon was proclaimed dead, and Ozai was announced as his willed successor. It is unknown what part Ursa had in these scandalous events, but it is almost certain that she played a major role in protecting Zuko. In Ursa's final appearance in the flashbacks, she wakes Zuko before her departure to remind him of her love and to tell him to always remember who he was, no matter how things seemed to change."

NOW with that said, when Ursa disappeared, rewatch the episode and what she says.?? We have an idea what she means since the creators gave us the parallel screnario in the same episode using those TurtleDucks.?? So here's one possibility - Ursa felt her child was in danger because of the actions of her husband.?? A mother will do ANYTHING to protect her young.?? Ursa was not dressed as someone who was going to the slaughter to sacrifice herself, she pulled a hood over her head, SHE WAS LURKING.?? Was she on the prey - would anybody even think that a woman would dare attempt an assasination??? And even if she succeeded, who would protect her??? And??was some agreement made that by allowing her to walk away that she would never mention??the??outrage that Azulon displayed at even the thought of him passing by his first born.

Now where you may ask does the ??Order of the Whilte Lotus come into the picture.?? Remember, Iroh was writing those letters back home to Ursa.?? His letters would be considered priceless to any resistance forces trying to get an insight into his battle plan at Ba Sing Se.?? Ursa's slip into the night was quit similar to Iroh's in "The Desert".??

I know there are ALOT of things that would have to be for this to be a possibility and maybe this should be listed in Spoilers and Speculation.?? BUT since there is no thread on the Order of the White Lotus OR a thread on Princess Ursa, I figured I would begin this one.?? And if there are threads on this topics I stand corrected but I can honestly say I typed both in the search engine before beginning this one.