Disclaimer: I don't own Harry Potter.
Hatred. The suggestion…the temptation to hate.
At first, there were no words.
Only emotions.
They didn't vary much—Harry could only think of three emotions. Granted, even at the age of six, he didn't know very many. Growing up with mentally—and occasionally physically—abusive relatives tended to stunt one's growth in all matters related to (and even outside) one's feelings.
Suggestion. Temptation. The act of luring. If that was an emotion (and to Harry's six year old, undeveloped mind, it was), that was the first one. However, it was mostly associated with the other two.
Pride. Or rather, the suggestion of pride. The entity was suggesting that Harry had not nearly enough pride. Because of his unknowledgeable mind as a six year old boy, Harry also put the emotion of smugness under the emotion that he categorized as pride, but he did not know that it should be anywhere else. To him, the feeling of smugness was always associated with the emotions of pride that the entity sent him.
Hatred. His hatred needed to grow. But yet again, the suggestion of hatred was what the entity was asking, or maybe giving, or possibly ordering. But Harry did not know of this hatred, and he did not understand what the entity was asking, or giving, or ordering for.
Eventually…words came.
"Hate them for what they've done to you, Harry."
"Hate them. Don't you feel it? The hatred that is inside you."
"You deserve better, Harry. They aren't giving it to you. So do something about it."
"Kill them."
At first, Harry the six year old did not listen. He was not interested in learning this so-called hate. For as a stunted six year old, Harry did not understand which emotions he felt inside were which, and he could not distinguish that which the entity was speaking of. Harry had grown up with the Dursleys, and one thing he knew for sure about them was that they didn't like questions. Harry had begun growing up without the satisfaction of knowing the answer to things he wondered about, and it had started to catch on. Naturally, Harry gave up on ever getting the answer to things he misunderstood, and he gave up like most children eventually would. They were easily distracted creatures, and since Harry's attention was not caught by the entity's words, he focused on other things. Mainly, the workload forced upon him by his relatives.
Very quickly, the entity learned that talking of emotions the boy did not understand would not get him anywhere.
This was where a new emotion, and a new feeling, was added to Harry's repertoire. Understanding. Harry knew that the entity now understood that which would get his attention, and that which would not. It was a very unique feeling, however, because the emotion of suggestion was not given to Harry along with the act of understanding. This was because the entity was understanding. Not Harry.
The entity then began to teach.
Harry listened. Harry learned. Harry understood.
But he was not sure if he should act. The suggestions the entity was giving him…Harry was unsure if he should go through with them.
Should he hate, as he had been taught?
Should he kill, as he had learned?
Harry did not know. The entity was forever persistent, and slightly impatient.
And so Harry learned of impatience.
For a long time, Harry thought on his learnings.
For a long time, Harry contemplated.
At last, Harry decided.
If Harry had been brought up in a world where the entity did not give emotions and did not speak, things would have been much different. If Harry had learned of Hogwarts a little after his eleventh birthday, via Hagrid the gamekeeper, Harry would have been a kinder, nicer Harry than six year old stunted Harry. If Harry had been sorted into Gryffindor, and become best friends with Hermione Granger and Ron Weasely, and defeated the Dark Lord Voldemort, Harry would have known of the emotions of happiness and friendship and even grief.
But six year old underdeveloped Harry did not grow to become Harry Potter, Savior of the Wizarding World.
Instead, Harry listened to the entity.
The entity that was never supposed to be an entity at all. The entity that was never supposed to speak, or interact with Harry, not even till the day it was taken out of Harry. The entity that was a piece of Lord Voldemort's soul, stuck inside Harry on the day the Dark Lord tried to kill him as a child.
And so Harry listened, and obeyed, and killed, and manipulated, and eventually caused much chaos in the wizarding world, in Voldemort's stead. And so he was "bad" and "evil" (according to many, who only realized too late), and only learned of emotions of pain and sorrow.
Harry also learned of regret and loneliness.
But that didn't metter, because only his subconscious did, for Harry had no one to tell him that these were the emotions he was feeling. He had no one to teach him, other than the entity that manipulated him. And the entity did not want Harry to learn of these emotions, for the entity that was Lord Voldemort did not want his puppet to break free.
No, he only wanted to give what he considered useful emotions, and leave others to waste. For he was the entity, and also, to stunted Harry, he was also his one and only trustworthy companion. In Harry's stunted, childlike, still-six-year-old mind, the entity Lord Voldemort was God.