How to enforce campaign themes

So i’m going to run a Giant campaign with 2 main themes: demigods (and becoming them) and Creation

The second theme is already accounted for, as each giant race will be able to create that which they represent and use those things in different ways, but i’m having trouble with the second thing (demigods)

Besides the big bad being a demigod (Scion of Surtr) i dont see how i could enforce these themes.