Imperius
"The visible horror has less power over the soul that the imagined horror".
William Shakespeare
HARRY HAD ALWAYS BEEN AFRAID OF CONTROL. His Uncle, Vernon, had always liked being in control – he really enjoyed. Harry, on the other hand, hated the fact. The control in his uncle's hands meant, in general, unhappiness.
Not for the Dursleys; but for little Harry. And with unhappiness came the pain and the suffering. Little Harry did not want to do freak things – as well as his Aunt Petunia stressed. He didn't want and, at the same time, he wanted.
In those moments, where magic happened, Harry could imagine himself in control of everything. He could make his own hair grow, shrink big things, even fly. And his Uncle and Aunt seemed afraid of the fact, or the least thought. Then, Harry knew he was in control.
Later, years later, Harry found another meaning for "control". It wasn't unhappiness, pain or suffering. The control, however, neither was tinged with joy and bouncing bunnies. He had a bitter taste in his mouth… Anticipation? Or was pity?
After that, Harry decided it would be foolish to be afraid of the control. His Aunt and Uncle did not control him anymore, as well as the power was not happiness or sympathy for those who are afraid.
And, so, Harry just threw the Imperius Curse off his mind.