Orochimaru
When he had been a little child, when his shinobi skills hadn't shown yet, the others used to tease him.
They said that he looked like a girl with his long hair and that he was a freak because of his snake-like eyes. Yes, he did have some similarities with snakes, but that wasn't a reason to tease him, was it?
As time went by and the snake comments got more frequently, he started to hate snakes. He detested them.
But a certain event changed his mind forever. (Well, there were other events too, but...well. They're not important now)
When he had been sitting in the grass, reading a book about Nin-jutsus, a snake suddenly appeared. "Go away!" he told it, but instead of obeying, it came closer and closer. It was quite giant snake and even Orochimaru, who had no interest in snakes at all, knew that this was a very poisonous snake.
Still, something about it captivated him and he wasn't able to do anything. He watched as it drew closer and closer. Then he snapped out of his daze. What the hell was he doing? "I said GO AWAY!" he shouted at the reptile. But that didn't stop it.
Instead it slipped around him, effectively circling him and he was unable to escape. He was tempted to stab it with a kunai. Really, he was. Yet he knew that that would be useless; the scales were too thick.
So he just sat there and waited for the snake to disappear. Or die, whichever comes first.
Suddenly he heard the voices of other children behind him.
"There he is!" they shouted and normally, he would've stand up and blocked their punches or kunais or shuriken or whatever they decided to throw at him. But the snake just wouldn't let go. And so he remained where he was and didn't move.
Then it struck him.
Those guys were already Chu-Nins. Chu-Nin means dangerous jutsus. And Orochimaru had just entered academy.
He waited for the attacks to hit him, but nothing came. Well, not nothing, but at least not that what he had expected. The bullies started screaming at the top of their lungs, sounding like little girls. ('Tch. Who is the girl NOW?') Orochimaru forgot all about the reptile and turned to look at whatever was causing their distress. To his surprise, it was the snake.
It was hissing at them, bared its teeth and was dangerously close to the Chu-Nins who apparently weren't strong enough for a snake like that. And so, they're only option in a situation like this, was to run. And they did.
Orochimaru stared at the monster-like animal. Why had it attacked the boys, but not him? The reptile returned to his side and looked up to him with its yellow eyes. "You...protected me...?" asked the dumbfounded boy. The snake...nodded?
"Do you want to be my friend?" And the snake nodded again. Orochimaru suppressed a squeal.
That was the start of a wonderful friendship.
(To say the least, his parents had not been very amused when he had brought it home. Unbeknownst to them, he had still kept it in his room.)