TLDR: A Fey Sorcererous wrongfully accused of being a changeling as a child. She hopes to become a true Hag by embracing her Fey Bloodbline and destroying the humanity within her.
As a baby, she seemed like any other. But as she grew older, she began to show signs of cruelty. Although she was rarely violent, she was often found convincing others to attempt dangerous feats of bravery as she would watch. Her most genuine laugh only ever emerging when they would fail.
Concerned, her parents sent word for a Cleric to visit and assess her. His diagnosis? She was a changeling, and it was her destiny to transform into a Hag on her 18th birthday and her mischief would only grow the older she got.
Fearing her eventual transformation her parents attempted to drown her in a river on her 16th birthday. She survives, by accidentally sending her father into a fit of magical laughter and shoving him into the water where he drowns. Later, she would return and kill her mother in the same way.
Although the accusations of being a changeling would prove untrue, she believed and embraced her supposed fate. She lived her first few years as an orphan in the forest, luring travelers to the river where she'd drown them, before stealing their goods and supplies.
As she approaches 18 she seeks out her soon-to-be hag sisters, only to be tricked, enslaved, and told the truth about her false fate. Her new Hag Mother claims to take pity on her but senses her Fey Bloodline and seeks to exploit it.
The hag claims her gullibility and humanity are the reasons she could never transform into her true Fey self. The hag uses this to leverage her into doing her bidding. Sending her to lure victims into her domain, often goading Munta to commit cruel acts and atrocities with the promise that this will starve the humanity within her and bring her a step closer to her true Fey form. After years of servitude to her Hag Mother's coven claim her time has come. They will perform a ritual to release her fey bloodline and allow her to finally make the transformation and join the coven as a Hag sister.
However, they betray her. The coven trap her within a ritual to harvest her darkened heart they'd been blackening for years. The betrayal, intended to be the final blow to completely darken her heart is interrupted as a band of adventurers invade the domain and attack the coven. Mistaking Munta for just another victim they liberate her from her Hag Mother's domain. They escape but fail to defeat the coven.
At first, haunted by her Hag Mother's hex magic she runs. But as the Hex magic fades with time and distance, she finds herself staring at her own reflection in the glass of a closed storefront. Seeing her own appearance for the first time in years she realized just how much time had passed. She was no longer the little girl that had foolishly stumbled into the Hags domain, nor was she even a young woman. She'd... aged... and it showed. The fear of her Hag Mother evaporated and was immediately replaced with a fear that things would end too soon. Angry at her parents for bringing the cleric into their home all those years ago and filling their heads with accusations. The fear turned to anger as she thought of the time she'd wasted with the Hag Mother, only to be betrayed. Her anger blossomed into rage as she turned from her reflection.
Her heart was in fact blackened by the time spent with the coven. In her frenzy things began to become clear. It wasn't because she was weak at all, she told herself. No. It was because of her potential. They feared her ascension and wanted to stop her, her voice stated within her mind. They wanted her power for themselves and THAT is why they wanted her heart.
Her path forward was obvious. She would do what she knew she had to, that her Hag Mother had been sabotaging all along. She would extinguish the humanity within her, embrace her fey bloodline, and transform into the arch-fey she was destined to become. She would challenge her Hag Mother and assume control of the coven, or destroy it and build a new one, she hadn't yet decided.
But first, now that she was free of her Hag Mother, there was one other issue worth addressing. The matter of that cleric...