The reveal in episode 2 that Ange and Princess Charlotte swapped identities in the past puts all of their previous interactions in a new light. For example:
The reason why Ange is chosen for Operation Changeling is due to her skill at impersonating Princess Charlotte, because she actually is Princess Charlotte.
Princess Charlotte acts very friendly with Ange, who by all accounts should have been a complete stranger, and in contradiction to Dorothy's observation that Princess Charlotte does not go out of her way to make friends. However, it turns out Ange and Charlotte already knew each other.
The entire opening conversation between Ange and Princess Charlotte is a veiled way for Ange to confirm her identity to Princess Charlotte without tipping off Beatrice or Dorothy.
Princess Charlotte mentioning to Beatrice that she'd rather be friends with a lying devil. Both she and Ange are effectively living a lie, making both of them "devils".
Princess Charlotte musing that some lies have the potential to become truth, while gazing at a family photo of "herself" with the Queen.
A smaller thing that makes complete sense after Episode 8 - why Ange had such faith in Princess Charlotte being able to not only hide the key but be able to take her antigrav device without anyone noticing? Princess was once upon a time a pickpocket.
Why the hell would Ange and Dorothy allow Beatrice, of all people, to keep the pen-gun, after Charlotte nearly shot someone with it? There's a decent chance a small gadget like that can only fit one shot in the first place. There would be no danger in giving it to Beatrice, and letting her think she was armed would make her more comfortable in going along with the mission.
Episode 3 is very good, if subtle, at showing how Beatrice has all the potential to be a great spy; she guesses correctly about the original Operation Changeling as soon as Ange shows she's able to pass as Princess, is shown able to read a blueprint quickly, shows courage when it matters, and is quickly able to improvise on her feet in a stressful situation; with the latter having her make use of something she is shown earlier in the episode to hate. Beatrice is naive and new to spy work, but her abilities to be a good member of the team are established in her first focus episode. This comes to a head in the finale where she's tapped to be involved in Dorothy's counter operation against The General.
In the English Dub, Beatrice possesses a deep voice, making her sound a lot older than her actual age is. However due to Beatrice's past, it's likely she doesn't even know what her actual voice sounds like and the choice is born from the desire to present herself as powerful to show that she can protect her beloved princess.
The same, in a different way, can be said about her high pitched voice in the original Japanese; the mechanical voicebox was forced on her when she was very young so by trying to reproduce her original voice, she ends up giving herself a "childish" one as a result.
While we get visuals what Charlotte (the real Ange) had to go through to become the Princess, we aren't shown what Ange (the real Charlotte) had to deal with when she was stuck in Commonwealth. From the looks of the place, it isn't far off that child labor and prostitution was part of the everyday life. Whatever Ange went through that the next time she met Charlotte, she just wanted to take the Princess to Casablanca and stay there.
The ending of Crown Handler, Part 3, has Team White Pigeon being ambushed and captured by the Duke of Normandy's men. While he may have suspected Charlotte was a Commonwealth spy, he would've needed to know the exact details of their plan to extract Princess Mary in order to capture Team White Pigeon as easily as he did. In other words, someone in the Commonwealth's spy network must have ratted the girls out to the Kingdom.
