Orochimaru
She was the real reason he did what he did in those experiments, he wanted to have her back to take her back from the cold grip of death that his village had cast her into.
Yet, they wanted to stop him, stop him from getting her back?
No, he would not allow them to stop him it was their fault that she was gone in the first place!
So he had fled his village and joined an organization hell bent on taking over the world.
He figured once they had control of it people would leave him alone to further his goal of bringing her back.
Yet they were too focused on other things so he had left them as well and started his own village and this time he knew, he knew this would be his last chance to bring her back, to bring back his Kagome.