Ismira Stronghammer was the daughter of Roran and Katrina, born during the summer after the war and death of Galbatorix.
The child was conceived before Roran and Katrina were officially wed, although the couple was married shortly after they realised Katrina was with child. Besides themselves, only Eragon and Nasuada were aware of the illegitimacy of the pregnancy, while everyone else believed the child was conceived after the wedding. Katrina stated that she would do anything possible to protect her child and even considered leaving the Varden after Ismira's birth to care for her in an environment not so threatened by war and struggle.
Ismira was born a healthy baby with a lock of red hair upon her head and an especially loud cry. Eragon commented that she had a strong grip, as she grasped his finger in her small hand. She was named after Katrina's late mother. According to Christopher Paolini in a 2021 Reddit Q&A, her father's nickname 'Stronghammer' became the name of his house and therefore Ismira's surname in lieu of the traditional patronymic/matronymic naming convention of Carvahall (in which case she would have been called 'Katrinasdaughter')[1].