Sorry, I have to be a nuisance, but there is a couple of things I disagree with here or would like to voice my opinion on. I am not saying that Obito was
scared of Itachi per se, but there hasn't been any clarity defined by the topic creator on what is meant by
scared. Though it may seem obvious, it actually isn't for I can easily parallel
cautious and
scared.
Obito had akatsuki under his control and if he so chose, he could have commanded them to eliminate Itachi for him if he posed a threat. And there's no way Itachi could solo Akatsuki.
But he
didn't. To the Akatsuki members, Pain was the leader and Tobi was just Sasori's replacement and Deidara's new partner. So how could Obito "command" them? Secondly,
why would Akatsuki attack Itachi for the action doesn't fall under any of their goals. If anything, Orochimaru was a greater thorn than Itachi, and yet he got off scotch free because attacking him would be very irrelevant to the Akatsuki as would be attacking Itachi.
Obito stated that Sasuke's power will surpass Itachi's....so why would he risk giving Sasuke the EMS if he is already afraid of Itachi? Not to mention he already threatened to kill Sasuke if he doesn't obey which means he's unphased by their power.
Because Sasuke has already been manipulated by Tobi and therefore not a threat. Whereas someone like Itachi is a little bit more difficult to read and manipulate. Not to mention, Sasuke's ultimate goal is to destroy Konoha (and everything else I suppose), which goes hand in hand with Tobi's plan, so they're both assisting one another. Itachi's ultimate goal on the other hand did not aid Tobi in any way and in fact, it conflicted with his objective(s), albeit just a little.
They made a pact when they first met. Why would Obito be afraid of Itachi if they just only met and knew nothing of his powers? He could have just attacked him and tried to end his life, but he didn't. He just came to honor his agreement in exchange for help get revenge against the Uchiha.
Even if they just met, there was more than enough valid evidence to prove Itachi to be a worthy adversary. He was just a kid and led the ANBU squad - a group in which Kakashi was a part of (if Obito didn't know this, it'd be fair to say that he suspected it would occur in the very least) and you knew what Kakashi was capable of already as a kid. And now we have someone even younger leading said group.
Not only that, but you find out that he was tasked with killing the
whole Uchiha clan in which he was up for. One kid, tasked with killing Konoha's (arguably) most potent and strongest clan. Those two alone gives anyone reason to "fear" this kid.
And lastly, he's an Uchiha; honestly the name alone says that his prowess is potent (according to the manga).
He would be more afraid of Nagato's powers than anyone elses
Except that he more than likely didn't know what the Rinnegan (yes Madara "told" him, but seeing the application is different) was capable of nor how proficient Nagato was with it. But he
does know that Itachi is an Uchiha, a clan in which he knows what they're capable of (which is why he kept telling and automatically assumed that he would surpass Kakashi once he awoken his Sharingan). He may not know what Itachi himself is capable of, but as I mentioned before, he's tasked with exterminating this whole clan (and not just
any clan), and that obviously says something.
He still had the powers of mokuton and the sharingan. Even as a kid, he did more damage than most characters and experienced more terror.
Yes, that is nice, but what does it mean? That he shouldn't fear anyone because he possesses these two great attributes? He wouldn't be so stupid as to think that he is invincible, considering that he tried attacking Konoha (with the Kyuubi might I add) prior to, and was forced to retreat due to defeat.
Obito could still control the Gedo with just the sharingan and Hashi cells. He knew the kinjutsu of the Uchiha along with other techs which Itachi had no knowledge of.
To be fair, Madara was only stating what
should be possible, but we know that theoretically speaking isn't always factual in application. We didn't see Tobi control the Mazou until he had the Rinnegan, so it is quite hard to say for certain of the aforementioned statement. As for the jutsus that "Itachi had no knowledge of", it is once again quite difficult to make such a statement with absolutely certainty, for there is no reassurance of such claim.
He already met the most terrifying force in the Naruto, Madara Uchiha, so why would he be afraid of someone like Itachi?
Because he met a Madara as an ally and already on his deathbed, not as an enemy.
Secondly, don't think that Itachi's the only one in Narutoverse that holds the title of "The Man with The Plan". Remember, Obito has done the following:
1. Taken control of the Akatsuki
2. Manipulated members of the Akatsuki to his will behind the shadows
3. Took on the persona of Madara Uchiha, a secret that would have been kept had Kabuto not summoned Madara.
But none of this really sputters to intelligence. Firstly, all he had to do was remain hidden in the shadows and have Pain do his bidding. Nagato is still pretty much a child and only seeks peace, which he knows his small operation in Amegakure was not going to accomplish. Offer him a resolution for that peace to become global (just like how Madara got Obito hmmm?) and you've just spun him into your web. Secondly, a lot of the Akatsuki were 'criminals' or just wanted "a better life" or so (i.e Orochimaru), therefore it wouldn't be too difficult to have them join your gang. And once you already have a few potent forces, collecting the rest is child's play for no single individual would so easily be able to ward off the potent forces coming to recruit him (i.e what happened to Deidara).
Bottom line, was Obito afraid of Itachi? Maybe, maybe not, you'd have to be clear when defining
scared.