Some amusing theories over why Kattappa killed ‘Baahubali’
Well, the first theory is that Kattappa is possibly not as loyal to Baahubali as he is to the throne. As Baahubali falls in love with Devsena and breaks the promise of Rajmata, Kattappa has to serve the throne and kills Baahubali.
Another possible theory is that he killed Baahubali on the orders of Rajmata. Well, it's a known fact that Rajmata was the mother of Bhallala Deva and after appointing Baahubali as the King, her son Bhallala Deva got furious and had an argument with his mother. She realised her mistake and ordered Kattappa to kill Baahubali, so that she can make Bhallala Deva the King.
Well, if you clearly notice the last scene from the first part where Kattappa is stabbing Baahubali with a sword from the backside, it could also mean that Kattappa did not kill him on purpose. By that we mean, Kattappa being a man of his words, would not kill Baahubali from behind as that amounts to cheating. He probably didn't realize it was Baahubali and mistook him to be an enemy and attacked from behind.
Since both Baahubali and Bhallala Deva are in love with the same girl, Devsena, Bhallala Deva decides to finish Baahubali and orders Kattappa to kill him in the war, so that he can claim the kingdom and Devsena together.
Did Kattappa actually kill Baahubali or wait, he didn't, maybe! He was just bluffing and in reality he did not kill Baahubali. It was Bhallala Deva who killed Baahubali, but Kattappa was told to hide the reality and took the blame on himself. Also, if one can vividly recall this new still from the second part which was unveiled last month, it shows a completely different scenario. You can see Kattappa bowing down to Baahubali. So, does it mean, he never killed Baahubali? Let's wait till the movie releases.