Background and early life
At some point, Yara and Lev's mother joined the Seraphites and lived on their island for many years. She eventually gave birth to Yara and Lev and raised them in the Seraphites' beliefs. She was so deeply religious, she made it mandatory for Yara and Lev to learn the words of their prophet.
Upon learning Lev identified as a man rather than a woman, their grief-stricken mother banished him from her home. Yara, defying her mother, chased after Lev to help protect him from Seraphites' searching to kill him. With Yara and Lev branded as apostates, their mother disowned them, starving herself in order to "repent" for their sins.
Events of The Last of Us Part II
Lev, not wanting to leave his mother behind, returned to the island in a boat to tell her how he felt. He hoped she would understand and leave the Seraphites with him. However, when he got there, she was enraged and attacked him in their own home, slashing at him with a knife. Lev fought back in self-defense and accidentally pushed his mother into the table, splitting her head open and killing her.
Distraught, Lev cried in the corner until Yara arrived with Abby Anderson. Devastated by his mother's death, Lev reluctantly left their home with Abby and Yara.
Yara and Lev's mother was a very devout member of the Seraphites. She was strict, borderline abusive, to both Lev and Yara as she wanted them to share her mindset. Their mother rejected her children's different views, especially Lev being transgender. According to Yara, her mother was not above violence against them if they were to do something that was against the rules, even attempting to kill Lev when he revealed his beliefs to her.
Yara and her mother did not get along, because Yara supported Lev more when he self-identified himself as male. Because of this, their mother disowned them. She prioritized her Seraphite beliefs and rules over her own children.
In spite of their complicated yet poor relationship, Yara was saddened by the sight of her dead mother when Lev accidentally killed her.
Lev and his mother had a poor relationship. She disowned Lev after he explained how he really felt about his gender. While Lev still loved his mother, despite the woman resenting him, she viewed him as an apostate.
When he returned, Lev's mother showed only hate towards Lev. Her abuse towards her son would be her undoing as Lev knocked her into a table, killing her but leaving Lev heartbroken from his actions.