I know that we already know the true reason why obito will come back to madara....
I just want to share a different story that might happen between obito and madara @ ch.606...

After re-reading the last chapter I realized that a short story(a summarized) like this might happen at ch.606...

@ the last chapter Obito thinks that he was in hell...



upon witnessing the death of his true love he will feel an emotional shock... he will cry and shout the name of rin until he will shout that he's better to die than to live....

He will also call the person living in the hell.... do you know who is that person? (read the panel below)



@ last page of ch. 606 Obito will call the shinigami and he will ask to take or end his life because he cannot live without rin....
The shinigami will slap :flaw: obito and will advise him that this is not the end of the world... i have a better plan.. and i want to share to you what is true love and true peace... End of last page...