The foreshadowing of Mastermind Parker
I remember I was a bit surprised watching s5 final scene where Parker essentially takes the mastermind role (probably because I wasn't paying attention). Since then every time I rewatch I'm unconsciously trying to find clues, not in s5, where there's even an episode about it (The Broken Wing) but in earlier seasons.
The Nigerian Job: There's this scene at the beginning where she asks Nate how does he know how many guards are there, and he tells him to count the haircuts. Parker responds with "I would have miss that."
And it seems small, but I think it's interesting to note that she's the one always learning these little things from Nate. If you compare it to, say, Hardison trying to figure out in The Real Fake Car Job how Nate knew everything would happen like it did, it tells you how they perceive the mastermind role: Parker sees Nate as someone who can teach her skills she doesn't know, while Hardison sees the Mastermind as someone all-knowing that controls everything, and has perfectly effective and intricate plans for everything, like a puppet master. When in reality you can tell Nate improvises things most of the time, even if he does have back up plans to fall back into.
The Bank Shot Job: Parker explains to Hardison how easy it's to rob a bank like that, displaying in her plans something that Nate teachs Hardison in The Gold Job: the best plans are simple and effective.
Parker: It's embarrassing. Everyone knows you don't rob a bank without an exit strategy. These two deserve to get caught. 42 seconds.
Parker: To rob this bank. One security guard who has never fired his gun before, 2 closed-circuit cameras outside, 1 inside, and a Glen-Reader safe built in the 50's whose default combination is the birth date of the manager's wife! Get in, get out, 42 seconds.
This also ties with something she says later to Hardison in s2.
The Bean Town Bailor Job:
Parker: I think people are like locks. Really complicated and frustrating. But you can't force them. You have to take time and be fiddly.
Parker: You learn to be patient, and just wait until you hear the...
(the lock opens and the door swings wide)
As a thief, she has to be able to unravel complex locks and security mechanisms all the time. Nate's great at getting inside the bad guys' heads and bringing them to their undoing. (As an aside, I like the fact that the show let us know that Sophie was perfectly capable of leading the cons if she wanted to, because she's also great at manipulating people).
And if she applies the locks=people thing to the plans she makes, it's not unexpected that planning a con and planning a theft would be quite similar to her.
Another point: as a thief pre-Leverage, she was always at more risk, not because she wasn't capable of defending herself, but probably because she had to avoid security guards and the like, and because she wasn't the best at social interaction at the time. Where Sophie would make the mark open the door, Eliot would barrel through any barrier and make himself an exit and Hardison would simply hack something, or not be in a place where he could be caught.
Parker would have had to make contingency plans every time she went to steal something. It's also because she's great at improvising, and adapting, which she hones over the years working with the team.
Nate: First Boston Independent, State Street Branch of the Boston Bank, Commonwealth Loan and Securities. Now...
Parker: First independent's got a Glenn-Reeder alarm system, series f-900. Two guards in the front, (laughs) one guard in the back. Cameras record, not monitored. Daily turnover, $2 million. State Street, mostly commercial papers and loans, but they do have bearer bonds in a basement lockdown room. Just takes a key and a retina scanner. Commonwealth (laughs) they-their alarm system's a holdover from the '70s, But (chuckles) But it's...
(everyone is looking at Parker, making her feel uncomfortable)
Parker: What? What do you guys do on your weekends?
She plans/analyses how to rob banks on her weekends, as a hobby. It's like Nate and Sophie's past-time being solving murder mysteries. Parker loves that kind of thing and she's great at it.
The Rashomon Job: She's the one that gets closer to stealing the dagger, and only loses it because she accidentally drops it and someone (cofsophiecof) took her duffle bag by mistake.
(Transcripts taken from here)
This feels like a rather incomplete post without any useful conclusion lol But my point is, or what I was trying to prove to myself at least, is that from the begining Parker was the best candidate to the mastermind role.