Charlotte raised Suzie too and Suzie looks like an outgoing and assertive woman. We can't blame Charlotte of everything about Emma either, her father abandoned her when she was a child and she has issues with that. Her shyness may be due to that, she has never had a boyfriend or a father figure in her life.
Now, when she is with the MC she has more confidence and behaves like a normal young woman and they barelly met.
On the other hand Charlotte has become overprotective of her because of the stalker. Charlotte thinks that Emma has become more withdrawn since her sister isnt at home, something normal because she is bullied at school but Charlotte doesn't know about that either.
So some of you are assuming that Charlote has had her isolated from the outside world since forever when that was never stated in the game.
