Sorry for the shortness, but it seemed like a good place to stop. Enjoy! (I don't own Harry Potter by the way).
Grinning like a maniac, the girl, Robyn, enveloped Harry in a big hug, tears streaming down her face. "I can't believe I finally get to meet you. I've been waiting so long." she whispered.
Harry forced a smile, and that seemed to satisfy Professor Dumbledore, because he left. When the professor was out of sight and earshot, Harry scowled and roughly pushed Robyn away.
"Listen," he said, rather rudely, "I have no idea who you are. You can't just come barging into my life like you've known me forever. I have one idiotic cousin and that's it!"
Robyn nodded, "Yes, Dudley's my cousin too. Of course, I'm not really related to him in anyway. You see, I'm your cousin on your dad's side. James was my uncle. I'll explain it if you like!"
Harry snorted. "Don't bother," he spat, "I have no idea who you are and I don't intend to, so just leave me alone!"
Robyn's face dropped. "But," she stuttered, "But I've been dreaming of this moment for so long. I'm sure it's hard to warm up to a cousin you've never heard of before, but you're the only family member I have left. Even your Aunt Petunia and Uncle Vernon aren't required to take care of me. I'm not at all related to them. I'm sure Uncle James would have wanted us to get along."
"Don't you dare bring my father into this!" Harry yelled, drawing attention to the odd reunion type thing going on, "Just leave me alone! I never want to talk to you again!"
With that, Harry stormed away, mad that a perfectly good afternoon had been ruined by this...this...imposter! He didn't even care that Ron and Hermione weren't with him. He would grumble to them later. And they'd obviously agree. Who did that girl think she was anyway? However, Harry just couldn't forget the tears lining Robyn's eyes and the flicker of hope across her face that was extinguished by his cruelty. Maybe, just maybe, she really was his cousin. It would be nice to be related to someone worth being related to. But Harry just shook the idea away. There was no way that girl was worth his time, and every second mattered.
Harry aimlessly wondered around the castle before returning to the Griffindor common room. Surely this is where Ron and Hermione would look for him. They'd be arriving any moment now, willing and ready to chat with Harry about that weird girl.
But after half an hour of waiting, Harry became bored and started his potions essay. He was nearly finished when Ron and Hermione walked in. Relieved, Harry stood up to greet them, but was ignored completely. They were whispering something to that girl, Robyn.
"Don't talk to him," Ron whispered.
"Just keep walking," Hermione added.
But Robyn stopped and looked directly at Harry. Her large eyes stared into his own, searching. And Harry found himself searching her eyes. Though as bright as ever, they were red and puffy, she had obviously been crying. Harry saw a little flicker of hope still burning, desperately trying to break through and come back full force.
"What are you staring at?" Harry asked curtly, crossing his arms over his chest and raising his eyebrows mockingly.
"Nothing," Robyn squeaked, lowering her head. Harry caught a glimpse of the tears sliding down her face before she fiercely wiped them away and ran upstairs.