I've been writing some character sketches inspired
I've never actively done character sketches before. I start writing, the characters emerge, and then I go deep to figure out who they are and what makes them tick.
Check out Angela Ackerman's latest blog post on The Bookshelf Muse blog. The blog has a thesaurus of character traits and the latest post is about traits for a guarded character. I'd encourage you to check out her blog regardless, the thesaurus covers all aspects of writing.
As writers we need to get inside our characters and see the world from their point of view. Think of yourself putting on big character driven goggles every time you write from that characters point of view so you can get inside their head and react as they would react.
If I did a character sketch of myself it would be of a writer who loves water sports but loathes getting wet, hates raw fish but insists on going for sushi, and who can survive for days in her writing sasquatch cave on nothing more than sour ju jubes and chai tea.
What kind of goggles would your character wear?