During this time, she developed a relationship with Bentley. After the Cooper Vault job, the both of them constructed a time machine. It was at this time that Penelope disappeared and joined forces with Cyrille Le Paradox in an attempt to sever all of Bentley's ties to the Cooper Gang and unlock what she believed to be his full potential, which was implied to be world conquest. She was defeated by the Cooper Gang and imprisoned, but later escaped and remains at large as a fugitive.
Role in the series
Penelope initially comes off as a nice and outgoing person. She enjoys utilizing her RC talents against enemies, and while doing so she can get a little excited. While Penelope had only been a member of the Cooper Gang for a short time, she was dedicated and loyal to her new-found friends, eagerly supporting them whenever they needed help. Unfortunately, her lack of physical prowess and abilities makes her rather timid when actually confronted by an enemy, but when someone she loves - namely Bentley - is threatened, she becomes a powerful combatant.
Unfortunately, at some point during her relationship with Bentley, despite the events that took place during Sly 3, she somehow became possessed by the belief that Bentley was being held back and controlled by Sly's morals. She began to develop a similar mindset to Dr. M, despite once being a moralist herself when she was an extremely firm opponent of cheating during the ACES competition. Of course, it's possible that her dislike for cheating and her violent reprisal against those who betrayed her Black Baron persona were a result of them going against rules she had set for the tournament, but only added to the point of her being moralistic. This is also backed up by her thinking in a way that Sly is evil and that his thieving capers are nonsense and for his own selfish gains, drawing a parallel to Carmelita Fox. With their combined intellect, Penelope started to believe that she and Bentley could have made billions in weapon design, and they could have ruled the world; she shares the trait of greed for money with the other Le Paradox subordinates, who all went to the past not just to follow Le Paradox's orders but also for personal monetary gain. She began to use and betray anyone to get what she wanted; in some cases, drawing a parallel to Neyla. She also began showing a more aggressive and angry side of herself, prominently when trying to finish off Sly and then, after a failed attempt to reason with her, tried to waste Bentley as a means of making their breakup official.
Later, in Thieves in Time, Penelope become very arrogant, proud, and vain. She believes herself the greatest genius, but knows - and refuses to admit - that she falls second to Bentley, blowing off Bentley's critique to her moat monster as a "prototype." She hates to admit when she's been outsmarted, especially when Bentley and Sly are involved.
She also became surprisingly cruel and gained a dark sense of humor as she even went as low as to torture Sir Galleth physically and mentally by putting him in the circus, and even joking about making a rug out of what was left of Sly once the Moat Monster was done with him. She also considered turning the Cooper Van into a clown car, even saying behind Bentley's back that she finds him "cute when he's being dumb."
At this point, Penelope's true character is a mystery. She also seems to be huge on masking her identity. Whether these are her true colors that were hidden from the Cooper Gang for a period of time or that they were somehow newly-developed is unknown, and disguises like the Black Baron or the Black Knight may not have been her first. Even how she obtained her skills is a complete mystery. Who Penelope really is may be unknown for quite some time meaning it is possible the personality she had in Thieves in Time may also be fake as well. Her actions, however, suggest more of an anti-heroine than an actual cold blooded villainess, since she openly admitted she was just using Le Paradox for her own personal gain.