First and foremost, there are very few things I choose to keep from the comics. I hate them.
Other aspects may be used for verses if a writing partner wishes, but that will have to be discussed because a lot of it does not sit well with me.
As for the actual tv show, the little we see of Ursa there (and I do mean what we see, not what we hear ("my own mother thought I was a monster")) is kept as well.
Most of my portrayal is based on headcanons. So here's a rundown of the very basics:
Ursa always loved storytelling, be it from others, or her own. It was only natural that such passion would lead her to pursue acting as well. It was when she was performing one of her roles, the Dragon Empress in Love amongst the Dragons that she and Prince Ozai first saw each other, but he did not yet know that she was avatar Roku's granddaughter.
My Ursa was not in a relationship prior to her marriage. While she wished to marry for love one day, she feared the consequences of rejecting Prince Ozai's proposal, and thus willingly went along with it.
Until the children came, her only complaint about her marriage was not being able to see her parents, speak to them. Once children became a part of it, so did a lot of other things.
Her husband had always wanted power, and their children were tools for it. His expectations shaped each of them in their own ways, and by extension, her own relationship with them.
She loved her children dearly - and equally -, but she saw too much of Ozai's worst qualities reflected in their daughter. However, Azula was young. She could change, she could be better. It was in hopes of steering her towards that change that Ursa would scold her.
By contrast, Zuko seemed to need more protection. Though that did not mean she simply allowed him to do whatever she wanted, Ursa did end up coddling him.
When she learned of Azulon's order that Ozai should kill Zuko, Ursa became enraged. She did not have much of a plan, but she knew she had to do something about it.
With the knowledge gained from her mother, Ursa poisoned the Fire Lord. With the man gone, there was no need to fulfill his demands. This all worked in Ozai's favor, as he desired the throne, but he could not trust that his wife's skill would not be used against him, and so he sent her away, making it clear that should she try to take the children, or show her face again, they would be killed.
Following her banishment, Ursa lives a quiet life in Ba Sing Se, under the name Reika. She owns an inn.
