The relationship between 2012 Leo and 2012 Raph is so deep and profound and powerful that it beats all others.
We as a fandom have decided to appoint those two twins, that should be a big enough hint of how close Leo and Raph are but there's so much more.
It not just big moments and clear ones but subtle things too. And while I can form a whole list of minute, ignorable moments from 2012 series that show how close this version of these two brothers are, there's one specific line I want to talk about.
Something Raph said in Broken Foot and the intonation of his voice as he said it.
"Remember how I wanted to dress up as the Night Watcher vigilante and you talked me out of it?"
Here's the thing, in that particular episode, Leo messed up. And it wasn't the first time that had happened but notice how this time, a part him knew he wasn't doing the correct thing while a different part said the opposite. Leo wanted to go out and destroy Footbot factories with Karai and Shini, but he didn't want to hide his part. That teenage part also just wanted to let loose without a responsibility of his team pressing down. Leo doesn't have his personal friends in this series like his brothers do and this might be the one time he felt like he was both making a difference and hanging out with his own friends but diverging from the point.
What I wanted to point out was Raph's words and how he tried to convince Leo to stop doing what he was doing with a means completely different from how he used to in earlier seasons. There are times when Raphael is the only one in the family who has common sense and he tends to observe and notice things which others aren't ready to accept. If you remember, the last couple of times Leo had trusted Karai, Raph was angry and annoyed. He had yelled at Leo but this time, he spoke kindly, in an understanding manner. Instead of outright arguing or refuting him, he related to him. And tried to remind him why this was a bad idea without revealing both their inner thoughts and reasons to everyone present. If you notice these two in the bg of the series, they communicate in a unique way, through silent looks and gestures nobody else seems to be privy to and they do it almost every single episode. Leo and Raph just, get each other. And this is why whenever they argue, it's usually over each other's flaws. They know one another so well that they argue when they know the other is making a mistake and is too stubborn to see it.
Anyways, in that episode, this one line indicates how Raphael was literally the only one who both understood Leo and was actually sincere with him without making him guilt trip like Splinter and April or manipulating him like Karai.
Moreover, it hints to a moment not shown in the series itself which deepens their bond.
Remember what happened the last time a Raphael decided to vigilante as Night Watcher and Leo found out?
But that didn't happen with the 2012 version. Leo managed to talk Raph out of it and Raph remembers that fondly with an understanding of the recklessness of the idea; "Just saying. It sounds like something I would do."
There was no fight, no epic dramatic battle, no such moment where one of them almost killed the other. No, Leo talked the reckless, stubborn, usually unreasonably hotheaded Raph out of it. Just like that.
And that, in itself, says a lot about how deep and profound their bond is. Leo and Raph have a special dynamic of their own in most iterations but in the 2012 series, it is something else entirely. It is so much deeper than it is in other iterations and I speak from the countless moments in canon. Not only are there numerous big plot relevant and noticeable moments of them supporting each other but also hundreds of tiny subtle moments of them understanding each other like no one else does.
