The Tailed Beasts
I wanted to have a discussion about the tailed beasts and why they "are who they are". We are going to assume that Madara was telling the truth and that they all came from the Juubi. The Juubi was apparently strong enough to bring destruction to the world. I wonder though, when the Juubi was split apart, why it is that Shukaku is the only intelligent one to date? Why does the Hachibi seem to be "good", why does the Kyuubi resemble the Juubi, and why is it supposedly the only tailed beast that can be controlled by the Sharingan?
I have a few theories about why these tailed beasts are. I don't make theories too often because I mainly just enjoy to read and argue about the manga. So please bear with me.
Since the Juubi was most likely unintelligent, it did things on instinct just like the other tailed beasts. However, it probably had a LITTLE bit of intelligence, and when it was split into the nine Tailed beasts, that was given to Shukaku. Then, when Shukaku was sealed (Shukaku was said to have had two hosts before Gaara), it learned to speak. Then it retained the ability afterwards. The reason I think Shukaku has intelligence is because when Gaara fell asleep during his fight with Naruto, Shukaku was able to speak. This could be argued that it is still technically sealed within Gaara, but when Naruto goes past the four-tails, he loses the ability to speak.
The Juubi had a massively overwhelming chakra that was evil. However, there may have been a large amount of "good" chakra as well. So the Hachibi may have been born from that being split.
As for the Kyuubi being connected to the Sharingan, I think it has something to do with the Juubi having the eye that had the tomoe on them. There may be a connection to that and the Kyuubi.
Now that I think about it, I hadn't really thought of how the Sage's boys, the decendants of the younger and the older, are able to control the tailed beasts. Hashirama can control them and he is the descendant of the younger. Madara can at the very least control the Kyuubi, and he's a descendant of the older.
What do you guys think of this? Feel free to add any thoughts of your own.