Alright after lurking for a very long time I'm finally going to make my first post/theory

.. Don't hate k? This is just my theory just ive been breaking down on tobi..like everyone else XD
First off i just want to point out some things about the Second Hokage, Tobirama Senju. Like the First he is directly related to the Sage. Obviously he has all of the knowledge of the past and is a genius. It was stated that he was practicing Space/Time Jutsu, like Tobi/Minato, but he never mastered it the way they did.
In the manga where he died we are introduced to Kagami Uchiha, who i assume was one of his students. As some people have stated he can possibly be Obitos father, but thats more assumptions. However, since he was trained by Tobirama I believe he has some basic understanding behind Space/Time Jutsu, Kagami (Who I believe to be Tobi) named his son in honor of his teacher, and his own Alias after him. He mastered what his master could not and he tried to teach his son some of it, or perhaps Obito saw his father practicing it and that is how he unlocked the ability to use Kamui, to which Kakashi now has. It can also explain why they share the same dimension
Kagami, who again i am assuming is Obitos father,and also directly related to Madara, would want revenge on the leaf for his only sons death, especially on Kakashi for not only letting his son die but also taking the eye of his son with the jutsu he mastered and his son witnessed, thus also possibly being a threat. Not to mention all his quotes of spite directly related to Kakashi it feels like Tobi hates him the most. Rin could possibly have seen what he was plotting and he silenced her as well as being a passive aggresive ******* on Kakkashi by eliminating the person he cared deeply for. He is also in the range to have known Madara and fight Minato, unlike Obito, and would want revenge directly on Minato for also not protecting his son.
Kakashi can use the Kamui because Obito had begin to unlock after witnessing his father practicing it and he had practiced it some.
In short Tobirama started to teach Kagami, who Kagami started to teach to Obito but he was killed and his sharingan was passed to Kakashi, which explains why Kakashi's sharingan can also use the Kamui.
There are some loops holes in this..such as assumptions and since Madara "died" before obito was born I am unsure as to how Kagami and he would have made their plans with Nagato's revival, unless there were more people involved such as Izuna still lurking around..Idk i have a lot of crazy theories
