Between Stone and Freya? Freya is actually the more talented of the two, and has even channeled Shiva already. I do like how they're deconstructing that though. Since she's growing too powerful too quickly, and as a result butchers most of her extended family in Lakluun. Which leaves her with PTSD. As that was done whilst Shiva took over her body. He went fire and brimstone on them after The Mother killed Freya, and they were under the influence of her spell. Rather than freeing them? Shiva just killed them for their transgressions against sinanju.
When power outpaces wisdom and self-control it leads to tragedy.
And I like how flawed they made Freya. Despite being the more powerful of the two she depends on her brother a lot for support. Same with her grandfather. Rather than "I don't need no man" it's "I hate this what I am becoming."