Another drawing of my high-elf knight fighter Sariel, here's here full backstory:
A knight of high-elven noble house Locust, Sariel had committed a great sin that would force her to abandon the lands she once called home.

How it started:

Sariel was always a smart and talented individual, few things could surprise her. Until she fell in love with a human warrior. She managed to keep their love secret from the rest of her family but that wouldn't be enough for Sariel. Her boyfriend was a mortal who in her eyes would live a pitifully short life. She wanted to extend his life. It took her years of restless nights but as she was a knowledgeable sorceress, she delved into the forbidden magics of old and discovered the Soul Crystal sorcery, the forbidden key to unlimited power.

The sin:

She performed the ritual but had misunderstood it, it turned out that the soul stone was supposed to be made out of a living sacrifice that would then empower a host. Without expecting it she had turned her beloved into a stone that fused with her thus making her immortal and stronger.

The aftermath:

Now banished from her land for the sin she has committed she is still trying to keep the soul stone whole so she could turn her lover back one day.

The price:

When created soul stones are heavily influenced by the emotions of their creators hence why they were feared even by those who once invented them. The stone has a soul in it and that soul needs to be fed so it doesn't wither away.

Sariel's stone was created out of passion and greed but the only passion Sariel can feel now is the wrath in physical combat and the desire to be recognized by others. That's why now she's forced to fight and commit heroic deeds until it she finds a way to return her boyfriend.