
Honestly I used to think that she only knew how to avoid conflict and run away. But now It seems to me that she tried her very best. She is living a life she never asked for, even worse than her real past life. She knew how and why her life was going to end and tried her best to prevent her tragic downfall.
She played by the rules and did her best to bring on her side those who she knew hated, ignored, and loathed her. When she finally thought she would be free, she was betrayed in the most cruel way because her most trusted person or "chance" brought back the sole reason of her (and real penelope's) suffering.
What can she do? She knows "Yvonne" is not human. She has no one to truly confide into in her own house and whatever she might say won't be taken for what it is, meaning the truth. She is mentally tired and physically worn out. They wouldn't even let her escape through death and ended up saving her life when she truly wished to end it.
I think her character is just realistic. She cannot do anything else except running away. And finally, she is even willing to stop "Yvonne's" plan in the process by hiding the mirror shard form her, and warning her father about her, despite the whole household taking her for granted for years.
She is an interesting character, and a well written one at that.
I feel like Penelope is slowly turning into a coward