Disclaimer: Harry Potter lives in JKR's backyard, I'm merely swimming in her pool.
It's a tasteful one. None of those annoying signs like, "Welcome to our L. You'll notice there's no POO in it. Please keep it that way," or anything like that.
Maturity can best be described as "one of those things." It's rarely interpreted as the same idea from person to person: some might think of it as being able to take care of oneself, others might see it as the drive to do what needs to be done when it needs to be done. Still others feel that maturity comes with age, wisdom, and experience, and that no matter how "mature" a child might seem, this child is still, in fact, a child, and prone to doing childish things.
Which may or may not be why Harry and Ginny's first fight had ended like it had.
How Harry and Ginny's first fight had started had little to do with maturity, in that neither was in possession of it, and more to do with temper, in that they both had too much of it.
He was brooding again. In his defense, he tried not to brood. He'd go days at a time perfectly happy, or at least secure enough in the illusion of it that he almost forgot the reality, and then something set him off again.
He didn't know what it was this time. He'd gotten through Defense Against the Dark Arts just fine, despite the discussions of Ministry positions, including the Department of Mysteries. He hadn't batted an eyelash when McGonagall had pointedly told them how not to be hit by five Stunners at once.
And then... something, inconsequential, no doubt. Someone mentioned the Chinese Zodiac, he remembered, which led him to think of the year of the dog, which led him to Sirius...
Which led him to the corner, reflecting on his darker memories.
"It's too loud in here," he finally decided, standing up. Maybe the library would be quiet. Well, the library would be quiet, under the unquestioned reign of Madam Pince.
He left the common room and headed down the hall. His arms were crossed, and his gazed aimed directly at the floor, which may have been why he ran into someone. "Sorry," he muttered without looking up.
"No problem," said a voice with which Harry associated red hair and violent cursing of more than one type. "You all right, Harry?"
"Fine," said Harry shortly, not particularly interesting in acting like he was when he knew Ginny would see through it anyway.
Sure enough, she said, "Of course. You sound fine. That would explain the monotone, the crossed arms, the distant look, the angry scowl. All merely signs of your fine-ness."
"You've got it," he said. "See you later."
"What is it?"
"Well, I know you get this a lot from Ron and Hermione, but if there's anything you need to talk about with someone who won't quote Quidditch Through the Ages or Hogwarts, a History, you can talk to me."
"Thank you," he said in an insincere tone of voice. "Are you done with me?"
"You're not the only one grieving, you know."
"I know. But I am the only one who isn't being permitted to go to the library." He tried to turn and leave again, but was stopped when he just barely heard Ginny say something under her breath. "What?"
Ginny sighed. "Bastard! I called you a bastard! You're so self-absorbed that you're starting to implode and suck the joy out of everyone else around you!"
"Well thank you for that warning. Let me be on my way and I won't suck anymore."
Ginny scoffed. "Yes you will, Harry. You might come back less depressed than before, but you'll go off again and you won't talk to anyone about it because you are a bastard!"
"I never asked your opinion!" Harry snapped. They had gotten quite loud by this point, and the only reason that they weren't drawing a crowd was that there was a vague fear of being caught in a crossfire of some sort.
"Well you got it! You think your pain is special somehow, don't you?"
"Yes!" Harry yelled. "Yes, my pain is different because it's my pain! I know how I feel! You don't!"
"I would if you would tell me! Maybe if you shared your pain instead of keeping it to yourself, it wouldn't be so bad!"
"Forget it! Just leave me alone!"
Harry walked away again, and Ginny, angry, breathless, and above all not finished, went after him. "Don't you dare think that you have the monopoly on guilt, Harry Potter! I am talking to you!" And then she did something she hadn't done since she was six.
She kicked him in the shin.
"You kicked Harry in the shin?" Hermione gasped.
"In the shin?"
"Yes, all right? I kicked Harry Potter, the Boy-Who-Lived, in the shin. And..."
Hermione raised an eyebrow. Disapproving and amused looks fought for supremacy, and disapproval was only barely winning. "And what?"
"I might have pulled his hair."
"Might have?" Amused was catching up quick.
"Well, definitely. He was asking for it! I don't like it when people don't listen to me." She had the grace to look sheepish, but witch's intuition told Hermione that there was something she hadn't been told.
"You didn't do anything else, did you?"
"No. Maybe. I might have..." she muttered something.
"Done what now?"
"I bit him. On the arm."
Amused was ahead by three lengths... a come-from-behind victory for the amused look. "Why?"
"It seemed like a good idea at the time. It was through the sleeve. He probably barely even felt it."
"She bit me, Ron! And drew blood! Through the sleeve!" Harry touched his arm tentatively and winced.
"She'll do that," said Ron, drawing on experience. "Best thing I can tell you is to apologize, mate."
"For being bitten?"
"Anything that ever happens to you is entirely your fault, as far as women are concerned," said Ron, drawing on even more experience. "Hermione and Ginny, anyway. Look at the bright side."
"What bright side?"
"You finally got a girl's mouth on you without her bursting into tears."
Harry glared at Ron for a moment, then grinned. "Shut up. I don't hear you bragging about your snogging exploits."
"That's because I don't kiss and tell."
"That's because you don't kiss, and thus have nothing to tell."
They laughed, and Ron decided to change the subject. "How'd you even run into her?"
"I was going to the library and I wasn't paying attention to where I was going."
"Ah. Did you get what you needed then?"
Harry had actually forgotten. He'd forgotten to brood, forgotten to want to be alone. Sure, it was only because of blood and violence, which was probably ironic, but still. He... felt... better. "I suppose I did."
"Good. Ginny's coming, by the way. You might want to hide your other arm."
Ginny was, indeed, coming. She was being pushed, actually, by Hermione. "Ginny," said Hermione pointedly, "has something she wants to say to you. Ginny?"
Ginny sighed. "I'm sorry I kicked your shin. And pulled your hair."
"And?" Hermione prodded.
"And bit you."
Harry felt tempted to laugh at the scene, but knew instictively that said course of action might end up being his last. "Well, I'm sorry I..." he felt self-conscious suddenly. "Will you two give us a moment?" he said to Ron and Hermione.
"Oh, a moment?" Ron began to say, but Hermione dragged him off before he could embarrass anyone.
After they were gone, Harry continued. "I'm sorry that I've turned into a joy vacuum. And that I was rude. But mostly I'm sorry that you bit me."
Ginny smiled. "You big baby, I bet I barely broke the skin. Here, let me see..."
Maturity is something that can't be defined as easily as, say, cake. Or perhaps it can. There are many types of cakes: many textures, flavors, and colors. Perhaps there are many types of maturity. Pulling hair, kicking shins, that's probably not the most mature thing to do.
But using the experience to help a friendship grow and to take another step closer to getting over the loss of a friend? Maybe that's a maturity all its own.