No, this is great! If you have more you're willing to share, I'd love to hear it. Very interesting.
Lol thanks... I left out this stuff as it is more like information that, after thinking about it, helps draw the idea of how they are related WHY they are related, and what they represent with that relation.
Alright, a second somewhat correlating piece of evidence are the eyes without power.
Hyuga- White
Uchiha- Black
They form a Yin-Yang especially with the colors as well as is a relevant Hyuga symbol. I'll also say how it could represent the good and bad of the Elder Son, but I'll come back to it.
Next up is actually looking into the eyes of Hyuga and Uchiha. As I mentioned earlier, the Hyuga's Byakugan could be seen as a purified eye, and white representing purity or enlightenment. If the Uchiha are a Hyuga Yin, then their eyes would be the opposite: Black and could represent corruption and ignorance (opposites to Purity or Enlightenment). This also seems plausible when you think of the Elder Son, and what happened to the Uchiha.
As we know, the hatred of the Elder Son came when being ignores for the successor position. We also know that the Rinnegan seems to be the final/ultimate eye the Rinnegan can become. It also seems likely that the Elder's Dojutsu derrives as some medium between Rinnegan and EMS. We also know this: the power of the Uchiha comes from love... And we know the Uchiha's power is the Sharingan.
Under say an ordinary living conditions, one could assume a son loves his family right? It would seem logical then, to assume the Elder truly loved his father and his brother. Now we take into effect three things.
1. Hagoromo dies
2. The Juubi seemingly was in Hagoromo when he had his children
3. Uchiha crazy syndrome (just laugh its a joke :rolleyes)
Being born, the Elder eyes likely have power from the Juubi: the tomoe shapes for example. Then with time, Hagoromo dies. Naturally, the Elder Son is devastated. Furthermore, his even more devastated as his bro is chosen over him. It's logical then, to presume that like his Uchiha descendants, the special chakra Uchiha have likely also effected the Elder son: my bet is this chakra relates to the Juubi's corrupting influence as it hates humanity for jacking its fruit.
Sorry to side track yet again, but keep in mind one thing: the Uchiha tablet can only be read by whom? Elder Son descendants.
To begin wrapping up, this means Hagoromo's intentions wasn't to put everything to the Younger Son.... But to trust both of his sons. Hagoromo found the Younger's ideal of love was the right path, and wished to encourage it. However, you can't get anywhere on your own. So Hagoromo trusted his Elder Son. The tablet was left to the Elder in hopes that when the Younger son sought the path of love, he'd have the power and wisdom the Elder Son had.
Sadly, the corruption influence mixed with jealously, and sadness (rooted in the loss of a loved one and what felt by betrayal of a loved one), instead the Elder Son turned to hatred.
The more and more generations that passed on hatred, the more and more they lost their true power. The Uchiha continued to turn away from love and focused on hatred. Continuing to run from the source of their power, the Elder Dojutsu just kept getting weaker.
Elder ==> EMS ==> MS==> The 3,2,1- Tomoe
And finally, their eyes burned out to empty black circles... Losing entirely their way.
BUUUT, we know people awaken their Sharingan: how so? ==> Love.
By searching and moving towards the original piece of power the Elder Son had (love for his family), he can regain his power in his eyes, and also picks up the wisdom to read the tablet. This also shows what Hagoromo originally wanted: to teach his Elder son that love was the key to his power and thus a key to peace... That the power to love others could unite the world.
And that's the detailed explanation of why the Uchiha represent Corruption or the Yin that balances out with Hyuga Yang. By having realized the fighting was useless, the Hyuga managed to keep from continuing to fall into the darkness; however, the ended up remaining as just that: observers.
Notice the lack of Hyuga action: Kurama attacks, Pain invades, Orochimaru invades... The clan doesn't act as a clan and help fight as we saw with say the Akimichi or Inuzuka. They passively observe. They notably have their own compound as opposed to other clans. They aren't even one of the first four clans present on Konoha yet a noble clan.
While they gained the wisdom to ignore the pointless hatred, they lost the drive to change the world and bring peace... Casting themselves to a simple observer.
Would also explain their lack of flashback.
So in conclusion... It seems we have this.
1. Rinnegan
2. Elder Dojutsu
3. Byakugan (white eyes) and EMS
4. MS
5. Tomoes
6. Black eyes