You ask questions which will reveal stuff I wanted to tell anyway in the future. Right now he is the grumpy communist who tries to kill Smirk and the crew with bad food.
But he has a sad backstory, so much can be told. Every crew member has a sad backstory and will get told here and there or becomes a main story.
A powerful portfolio is one that either represents your strenght or is showing that youre flexible in the forms of arts; having a variety of different stlyes in it. There is no real golden rule for a good portfolio, but make sure you check the studios preferences and try to adapt your portfolio to their ‘goals’.
Some peeps even like that you show your progress and how you improved in a short time. That is all i can say.
The rest is a lot luck and also a big amount of ‘social work’. The industry is not so much interested in quality anymore but more in how much you can work in a team.
Hope that helped!
Work as much as you can and always set your goals higher. Don’t destroy yourself, but also don’t sit in your own praise.