One of the earliest examples of Leo’s “I’ll do my own thing to accomplish our goal without discussing it with my team first” is in episode one. It’s super, super quick, and ultimately inconsequential, but it subtly sets up a great precedent that I think is very interesting.

When the boys need to grab the medallion from Splinter without Splinter noticing, Raph, Mikey, and Donnie huddle together with Raph taking the lead in trying to devise a plan to get the mystic device. Meanwhile, Leo slinks away and grabs the device by clocking the situation (by knowing his father well enough to predict his actions - something he does with each family member multiple times in the series) and making a move on his own.

It works out perfectly fine, and is ultimately the best move, and it’s honestly okay that he didn’t consult everyone for something so small when it’s such a non issue to get it, but it nicely sets up how this tends to go in the series, including how it goes in the movie.

To be honest episode one is actually really good at setting up a lot of things for each character in the long run, this is just one example that caught my attention, as small and unassuming as it is.