Pretending not to know anything was rather easy to her. It was something that came naturally to Drizella. She was used to being someone she wasn't.
And fooling her mother wasn't that hard given the fact her mother hardly payed any attention to her. Victoria spent most of her time either searching for ways to bring Anastasia back, or torturing Jacinda - neither of which Drizella paid much attention to.
Jacinda never doubted her step-sister for a moment, no thought in her silly mind that Drizella was acting. And Lucy never thought about it really, so certain Drizella trully believed she was Ivy - her attention too focused on Victoria and Henry, no time for her to think about the evil step-sister.
Even with Roni it was easy, simply pretending, making herself look like a foolish girl she actually wasn't.
It was different with Henry though. And a part of Drizella hated the way lying to him made her feel guilty. Because he was different, he didn't seem to judge her like everyone else. Henry actually listened to her, even at the moment when he didn't have time to do so - after all finding Lucy should have been his priority, far more important then listening to her sad story.
Which is probably why she was mostly honest with him. Never telling him the full truth, but still being far more honest then she had been in a while.
Because the guilt ate her up when she wasn't truthfull with him, making her feel horrible and evil. Feelings she hated with burning passion.
But it was true, wasn't it? She was the evil step-sister. So why did Henry Mills make her feel like she didn't have to be?