Kinda feel this story is so much the tragicest of tragic backstories that it's a little embarrassing to share, but since we're here...
This is also something I've developed and played with a lot while playing, so it's gonna be loooooooong...
My champion is a 5'2" catfolk courtesan female named Nyamh. Her mother was a courtesan who unintentionally became pregnant from a client, a minor noble in an old Belharran city named Lothian on the west coast of the continent.
Her mother had no desire to be a parent, and was generally neglectful and cruel; she was already a cynical, jealous and selfish woman, and blamed her daughter when her popularity took a dive after she mothered a bastard. Not knowing what else to do with her child, she had her trained to become a courtesan (including training her in a dance, music, literature, etiquette and how-to-steer-a-conversation-so-that-the-other-person-tells-you-their-entire-life-story), though she fired any nurse, tutor or maid whom Nyamh showed attachment to.
Nyamh's father had a desire to connect with her, but had a wife and legitimate children, and the former Belharan Empire being what it is, acknowledging his bastard could have turned her into a weapon his opponents could have used against him. He would visit her at her mother's house from time to time but didn't know how to connect with her, especially as Nyamh herself was emotionally withdrawn. As a child, Nyamh believed that if she could impress her father, by showing diligence in her studies, he would take her away from her mother to live with him. I headcanon that while her companions were freaking out when encountering the lureling, Nyamh was on her knees calling out for her father to save her. He was vaguely aware that her mother was abusive, but closed his eyes to the situation, not having a way to fix it. He would sometimes leave his daughter gifts, though these were usually taken or destroyed by her mother once he left.
Outgrowing her hope in her father also meant outgrowing any faith in the gods, Lumia in particular. I imagine her interactions with Lumia in act two being very difficult as a result. Though she's respectful, she's cool with Lumia and she particularly struggles to understand Ryn's faith since the goddess did nothing to save her from Alissa.
Nyamh can recall occasions when her mother would uncharacteristically share a kind word, take her for a picnic or do something else familial, before reverting to form a while later. Her mother eventually sold Nyamh's virginity to one of her clients, and shortly afterwards Nyamh left her mother's house, hoping never to see her again, and started her own career as a courtesan. She hated the work but didn't see any other path for herself.
She quickly became jaded by her role, pretending to have a relationship with noble men, hanging on their arms at parties, being seen, all for money; seeing the tawdry sides of nobles; making sex and courtship a mechanical process intended to maximise her partners' desire and pleasure; competing underhandedly with other courtesans for clients; having sex with men for money despite being mostly gay... She was sickened one day to realise she was becoming as bitter and selfish as her mother, but didn't see any way out of the life she was living. Then one day the political situation in Lothian went into upheaval after the ruling duke died leaving only a six-year-old heir, and Nyamh found most of her client base were on the losing side of the subsequent conflict, fleeing or being arrested or bankrupted. Faced with the prospect of rebuilding nearly her whole career from the ground up, she realised she could just... not. Reasoning that she'd rather die starving in a ditch than go on living her current life, she sold her assets, said goodbye to her few friends, abandoned her last name, and set out to wander the world, following where the road took her.
I headcanon that meeting Cait, a fellow expensive-sex-worker with a totally different attitude towards the work, had a huge impact on her, and talking (and sleeping) with her helped her overcome a lot of her childhood trauma and hang-ups about sex. Nonetheless she fully intends to flee the Frost Marches, once she's repayed Garth's kindness by helping deal with the trouble around Hawkethorne. Then she find's Kiyoko's amulet and becomes committed to helping her too (I tie this into my build as well - my champ's main use of magic is for summoning, which she learned to help, and with the help of, Kiyoko). But most important is Etheryn. Helping Ryn and seeing her courage, her determination to go back to the Winter City and fight to defend her people even without the support she came south seeking, and in the face of overwhelming terror... plus her unquestioning faith that Nyamh would help her confront Alissa, is transformative. In the end it's the unexpected affirmation of being made Champion of Hawkethorne and from Ryn's belief in her that finally inspire Nyamh to stay in the Frost Marches, face Kasyrra, and be the world's champion.
Moving well beyond backstory here but I really like to headcanon how her relationship with Ryn develops. By the time they're heading north to the Winter City, they're already falling in love, but neither can admit it - Ryn because she's too in awe of this woman who has shown her such kindness and whom she has seen help so many others, and Nyamh because expensive whores don't marry royalty, not even in fairy tales. During Spectre of the Wyld, specifically under pressure from the ghostly harem, Ryn and Nyamh finally confess their love for each other and Nyamh accepts that she will be to Ryn whatever she's allowed to be. I play through the Winter Festival before heading to Khor'Minos which feels very important to their relationship, with Nyamh fully opening herself up to Ryn for the first time. Then during Demon of Ice, during the boat ride to Dracia, Ryn refers to the champ as a future royal consort... Suddenly she's a lot more motivated to beat Alissa.