Okay so we are knee deep in the revelation that Tobi is Obito now so no turning back but for many of us this feels to be a great disappointment at the over seemingly simplicity of one of the seemingly darkest villains in them manga. Aside from the timeline conflicts there may very well be more to the story than we realize and I will explore some of that here but why dont we take look at some of the other villains in them manga and explore their transformation into villainy as a comparison.

Most of the characters that turned evil can be split into 2 camps. Those that had some traumatic life experiences and made an intellectual choice that led to an evil mindset and those who had traumatic life experience followed by periods of suffering that lead to an emotional turn to evil.

The Intellectual choice for Evil: I did it because I wanted to.

These individuals are marked by tragedies in their life which had a dramatic effect on their way of thinking. They became evil not because of rage but out of ideology to try and find greater meaning to life to validate there experiences.

Madara: - We don't know about his childhood but we do know it was a time of constant war that he grew up in thus death and sacrifice where a constant for him. Thus in order to gain greater strength eventually he killed his best friend and obtained the MS along with his brother that allowed him to take control of the the Uchiha clan. With this new power he was able to challenge Hashrima the greatest shinobi of the time. It was around this time he also was able to read more of the Rikudou Tablet left with the Uchiha.
As his eyes failed his brother Izuna sacrificed his eyes which lead to his death and he was able to obtain the EMS but before he could use this new power a Senju Peace treaty was sent which he opposed but the other members of Uchiha clan where tiered of war and wanted peace. Thus he was forced into an uncomfortable peace for the interest of the clan. As he tried to wrestle leadership control of the new village the Uchiha clan refused to back him thus he was force to leave alone. He obtained the Kyuubi and used it to attack but was defeated by Hashrima but not before obtaining a sample of his DNA.

Thus Madara who grew up during a time of constant war, who was betrayed by his own clan believes only in power and making sacrifices to obtain it as that is how he survived for so long. However interestingly enough the fact that the Uchiha betrayed him makes you wonder why he would entrust so much to Obito/Tobi.

Orochimaru: - He lost his parents when he was young and thus grew up an orphan without that parental love. Upon seeing the skin of white snake Sarutobi explained to him that it was symbol of rebirth and that perhaps a sign that he could see his parents again some day. Clearly loosing his parents was a traumatic experience and him being an intellectual tried to find meaning from this tragedy by buring himself in the study of jutsu. Thus jutsu's became an obsession for him and as he grew up during a time of war his mission experience grew and so did his experience with the fragility of life as death is everywhere in a Shinob war. He also joined Danzou's Root which teaches you to kill your emotions to become a more powerful tool. You can see plainly from his offcial mission logs how much war experience he has: Orochimaru has completed 1,468 official missions in total: 16 D-rank, 332 C-rank, 521 B-rank, 491 A-rank, 108 S-rank.

Thus his seeking to find meaning to life through studying jutsu plus his fear of death is what lead him to abandon morality & to become a villain.

Sasori: - His parents died when he was a child so he grew up without the warmth of his parents love but always secretly desired it. His grandma Chiyo raised him and looked after him as best she could but eventually he became a shinobi and went through the Sand villages indoctrination of "killing your emotions to become a weapon" training program. This was probably a relief to Sasori in that he always carried the grief of loosing his parents love and that left a hole in his heart which he tried to stomp out by learning to kill his emotions. However like in many other villages that experimented in this there was backlash in that a shinobi that kills their emotions can also loose something important like their moral center thus his killing the 3rd Kazekage to gain access to his abilities.

So you could say his seeking to conquer his own pain and fear of death to gain meaning from life was his reason for turning evil.

The Emotional Turn to Evil: Rageoholics unite

These guys didnt so much make an intellectual choice as one from strong emotions that stems from long periods of suffering.

Nagato: - This guy is clearly marked with a lot of suffering from early on. His parents where killed violently "trying to protect him" when he was child. His powers awoken and he managed to kill the attacker but all to late. Due to war and he became a war orphan & he spent his time wandering begging for food and almost died from starvation until he ran into Konan & Nagato. The war orphans had no one to rely on but each other thus became like family and struggled to survive by stealing food.
During his early time with Jiraya Yahiko was attacked again something he loved being threatened ad his powers awakened again and killed the attacker allowing him to protect his friend.

Years later during Hanzou's betrayal his most precious friends are at risk and he was "unable to protect Yahiko" thus he died. Thus he uses his most forbidden jutsu and destroys nearly everyone threatening his friends and is able to protect Konan.

Clearly the theme running here is his desire to protect the ones he loves while failing to do so twice and that pain fueling his desire for greater power the power of a god to protect those things. Very Anakin Skywalker like as mentioned years back in my starwars thread.

Gaara: - Clearly he suffered a lot as child his mother died during childbirth and he was born to be the secret weapon of the village. Firstly as Jinchuuriki he got the usual treatment of pariah of the village with the evil stares and the like. Then on top of that his uncle the only close parental figure in his life was forced to lie to him and tell him his mother never loved him and he wanted him to die and killed himself to do so. Then dear o Dad tried to send assassins to test his power which Gaara assumed where attempts to get rid of him because he was an unwanted relic of the village.

So as you can see Gaara's brief turn to evil was from obviously being loathed and hated and thinking no one loved him and thus he wanted to gain power to kill all those who threatened him and his existence.

Sasuke: - He had a normal childhood with a loving brother and 2 parents until that fateful night where the brother he admired and looked up to more than anyone else killed the Uchiha clan and his own parents then tortured him. Sasuke a small child at the time knew nothing about the internal drama of his clan and could hardly make sense of everything that happened to him. The most prevailing question in his mind was why? He wanted to understand why Itachi betrayed him and did such horrific things. After Itachi's death he learns the truth from Tobi and of course he becomes enraged because everything he knew about his clan and his brother turns out to be a lie. Even now with Orochimaru he seeks to uncover the truth behind everything to make his own decision.

Thus Sasuke's goal since the massacre has always been to seek the truth and seek justice.

So where does Obito/Tobi fit in?

Okay so based on his response "I was because you let Rin die" it would seem his reasoning would fall under the emotional category. Most of the guys under that category not only had tragedy but period of great emotional suffering. Clearly Madara is factor here too and I'l get into that.

Was Rin dying the only factor here?:

- I would venture to say no that doesn't seem to be enough reason to hate the world so much but it was defiantly a factor

So what was Obito's great suffering?:

- Well we dont know much of what happened during his childhood if he was a war orphan or not is unknown. How he was treated by the other Uchiha members is also unknown maybe he was looked down on as embarrassment to the Uchiha clan?

- The first obvious factor would be his injuries that he suffered from after being crushed by rocks loosing and arm and possibly portions of his body.

- The one thing I can link from both loosing Rin and his bodies damage is that these are both are the result from his own decisions in some way. He entrusted Kakashi to protect Rin with his sharingan and that failed. He sacrificed his own life to protect his friend Kakashi and suffered injuries from it. So he could blame himself for not protecting Rin with his own hands and believing in his own power to protect her rather than leaving it up to someone else.

The Madara connection:

- I have mentioned this before but I defiantly feel there is a direct connection between Madara & Obito and that he may actually be a decedent of Madara or Izuna. Thus Madara is not just a fellow Uchiha he is close family to Obito who for all we know may have been a war orphan of the clan. This may explain why Madara trusts him to some degree....

Madara may have explained his true heritage and that he is descended from greatness and instilled into him a greater sense of purpose and pride he never had.

- Also we know it is possible for Uchiha clan members to share memories through their eye Genjutsu, so its possible Madara gave him a lesson in hatred from his own vast life experiences. I'm speaking Clock work Orange type lessons here. He may have predicted the fact that Rin was going to die because he relied on someone without special power(Kakashi). Thus when Rin died it may have seemed like Madara was a prophet & the gospel and everything that happened was from his own foolishness.

- This still makes it hard to believe Obito could handle all the things that happened that night the Kyuubi attacked but hopefully there is reasonable explanation for that as well. However there is still probably more to it than that. Things we as audience member didn't know anything about that will be revealed.

Feel free to discuss!