OKAYSO. In my heart of hearts, Viserys was actually a good person originally but was warped by having such a horrific experience when he was so young and he was taught that he couldn't trust no one and the only way people would respect him and like him was if he had power. He just does whatever he needs to get it. And, his whole life, he's been jealous of Daenerys and doesn't understand why people always like her but hate him because he's the more powerful one and she doesn't have any power and it just confuses the hell out of him and he doesn't understand what he did to deserve this life.
And he has a really demented relationship with Daenerys where he hates her because she can do what she can't (be loved by people) but loves her for some reason he doesn't understand and sometimes at night he would watch her sleep and think about killing her because his life would be so much easier if he was the only Dragon and he'd like hold a pillow over her head but then he'd realize that he loved her too much to do that and it pissed him off so he makes up for it by being horrible to her and mocking her for her weaknesses which are really strengths.
OH. And he married her off to Khal Drogo to put her in a safe place where she couldn't get away from him nor could she steal his power because he expected the Khal to break her. He certainly did not expect them to fall in love. And then, when they do, he's so jealous because she can love and be loved but he can't and she was the only real relationship that he's ever had.
...... That wasn't supposed to be that long.