Yeah, Cas is definitely prone to jealousy, haha. They both have different strengths and weaknesses, which is good at least, because that makes them more complementary to each other.
It'll be really interesting to see what happens between them as the story progresses, because so far, they haven't had too many personal issues. Most of the time, it's them vs some sort of external stressor, but when things calm down, they'll have to learn how to handle conflicts amongst each other.
That's cool! My brother is a 5 :) 5w4, specifically. I'm a 7w8, which is very opposite in a lot of ways, haha. I'm pretty extroverted and confrontational xD
Anyway, I was running errands, but I'm home now, so I'll try to get another reply up!