As a fellow introvert, I felt a lot of pity for Bernadetta being so shy. I chose Edelgard and the Black Eagles, so she was in my main party.
Pre-time skip you rarely get to see her out of her room. Her excuses on staying put were kind of funny.
Post-time skip she matures a bit. She certainly has way more confidence this time around.
On the battlefield, she was a decent archer. But she could have been stronger on both the defense and offense.