Sirella was of noble descent, tracing her maternal lineage back to Shenara, daughter of Emperor Reclaw of the Second Dynasty. However, her 23rd maternal grandmother was actually named Karana, a concubine. (DS9: "You Are Cordially Invited")
Upon her marriage to Martok, she moved into his house. She "accidentally" left the door of the house open, allowing Martok's pet targ to escape. Even though she was responsible for the loss of the creature he had had since he was a boy, Martok later told Benjamin Sisko he would "not trade Sirella for all the targs on Qo'noS." (DS9: "Strange Bedfellows")
Although she was completely different from the woman Martok thought he would marry, his love for her was very deep.
She was opposed to Worf joining the house of Martok, but eventually accepted she could do nothing about it.
A proud and headstrong woman, Sirella was originally opposed to the marriage between Worf and Jadzia Dax, believing that by allowing aliens to join her house would threaten their identity as Klingons. Since as mistress she had the duty of approving all marriages into the family, she came to Deep Space 9 to evaluate Dax's worthiness. She was greeted affectionately by Martok when she arrived but she was dismissive of this and refused his offer to escort her to Dax's quarters. Sirella's views led her to set Dax's standards impossibly high, eventually causing a clash between them and to her canceling the wedding. Dax eventually begged her forgiveness, changing Sirella's mind about her. Sirella later performed the wedding ceremony. When the ceremony ended Dax bowed to Sirella and addressed her as "my lady" and the two women embraced ending their conflict. (DS9: "You Are Cordially Invited")
In 2375, Sirella sent Martok several cases of bloodwine. They were purloined by Nog as part of a business deal, though Nog was able to appease Martok with fifteen cases of a 2309 vintage, superior to the ones Sirella had sent. (DS9: "Treachery, Faith and the Great River")
The casting of Sirella pleased Martok actor J.G. Hertzler. He reminisced, "When I heard that Shannon Cochran was going to play her, I said, 'Perfect!' because she has a Shakespearean background and I knew we could really feed that into the two characters' relationship." Indeed, the portrayal of Sirella's relationship with Martok was influenced by the connection between Beatrice and Benedick in Shakespeare's "Much Ado About Nothing". (Star Trek: Deep Space Nine Companion (p. 504))
Jadzia Dax actress Terry Farrell was impressed by the portrayal of Sirella in "You Are Cordially Invited". "Shannon Cochran [...] was really good," she remarked. (Cinefantastique, Vol. 30, No. 9/10, p. 48)
Ronald D. Moore and Ira Steven Behr thought Sirella's ability to make Martok cower was very funny. Behr admitted, "I thought that Sirella was a hoot!" J.G. Hertzler felt likewise. (Star Trek: Deep Space Nine Companion (p. 504))
Ron Moore was additionally happy with the way Sirella supervised the Klingon wedding ceremony in "You Are Cordially Invited". "Sirella really delivered the ceremony with all the dignity and panache I was hoping for," Moore related. (Cinefantastique, Vol. 30, No. 9/10, p. 44)
Set in 2409, the computer game Star Trek Online depicts Lady Sirella alive and supervising the family estate of the House of Martok in the Ketha lowlands on Qo'noS. The following year, Sirella, along with Worf, lead a fleet of Klingon warships to the Briar Patch to provide reinforcements for a rescue mission undertaken by Rodek and the player to liberate her husband who is discovered to be alive and imprisoned at a Son'a prison there. Sirella was originally voiced by different actress, but Shannon Cochran reprised the role in a 2020 update.