I was thinking of my domain being fear, and my portfolio the unknown. As in fear of the new, different, unknown. Is that too broad?
Hello! Glad you're brainstorming, always good to see fresh thoughts.
When picking a domain and portfolio, my advice is to always consider concrete ways that you could use them. Fear (Unknown) isn't too broad at all, but what kind of creations or heros or miracles interest you about it? Do you think you could use it to solve all sorts of unexpected problems as they arise?
Feel free to drop more thoughts about your character or abilities here.