Flashback. May 1996, Iowa.

"Dean, hurry up or else we ll be late again." Sam and Helena yelled in unison as they waited for Dean to drop them off at school. Eentually after a few minutes he finally showed up. "Cmon, being a little late won t kill you." Dean said as he approached the two of them. They got into the car and drove off. Sam and Helena talked about some science stuff when Dean turned the radio on. "Do you mind turning the volume down? We re revising homework here." Sam said in an annoyed voice. "Oh sorry for interrupting your fascinating conversation, Mr and Mrs Geek." Dean remarked and grinned.
"Very funny Dean." Helena said sarcastically and rolled her eyes.

They finally arrived at school and Sam and Helena, who Dean usually referred to as the "Geek couple", went straight to class while Dean chatted up some Cheerleaders.
At lunch break Sam and Helena sat down at their usual table and watched Dean hitting on girls. "I can t believe that girls actually fall for the crap he s telling them." Helena commented as she saw Dean taking off with one of the girls.
"I know. It s been like that at every school we went to." Sam said with a sigh.
After a moment of silence, Helena spoke up. "Dad called me last night. He said that John and him would return tomorrow." Her voice was filled with sadness because she knew what it meant. They had finished the hunt and it was time to say goodbye and move on to the next town. She would have to part ways with Sam.
Sam and her had gotten close the past few weeks while their Dads were out hunting. They shared the same interests and had so much more in common. He knew what it was like having a hunter as a father and feeling like an outcast. She was able to be completely honest with him. She knew he would never judge her, he would just be there for her and listen.
"It s not like we ll never see each other again.. I promise I ll write and call you until we meet again." Sam said trying to cheer her and himself up. He was sad because he finally found a friend who was like him in so many ways.

The next day John and David returned. "It s time to go, Helena." David said as he took her bags and stuffed them into his car trunk. "I ll just go and say bye to the boys. Be back in a minute." she said and went back inside the motelroom that had been their home for the past few weeks. Sam was sitting on his bed all by himself while John and Dean loaded up their cars. He was staring at the floor, lost in his thoughts. Helena said down next to him and put her hand on his shoulder. "I came to say goodbye. We re leaving now." she said, fighting hard to hold back the tears.
Sam was cramming in his pocket and pulled out a little box. "Here, I got this for you to keep you safe."he said and handed the box to her. She opened it and looked in awe at the pretty silver protection bracelet. "Sam, it s beautiful." she said and hugged him. "Promise you ll call and write me" she whispered into his ear and gave him a peck on the cheek. "I promise." Sam said and pulled her into one last hug.
They finished saying their goodbyes and she walked out to her Dads car. John and Dean were standing next to him. "Goodbye Dean." she said and gave him a quick hug. "Is that it? You re not going to tell me how you re gonna miss me and my charm." he said and gave her a cheeky smile. She rolled her eyes at him and then turned towards John and hugged him briefly. "Bye." she said as she got into the car with her Dad. She looked back one last time and found Sam standing by his brother and Dad with his eyes fixed on her.

Helena was now all alone again. She tried keeping herself busy by doing research for her Dad and training with him. Sam held his promise and called every now and then to check up on her. Everytime she would look at the bracelet he had given her, she d remember the happy memories they shared.

A little later...

Helena graduated high school successfully and started hunting fulltime with her Dad.
Everytime they d go on a new hunt, she would pray for them to bump into the Winchesters but they never did.

2 years after graduation her Dad was killed on a hunt. She went on a vendetta against those who took away the only family she had left. Grief and the determination to have her revenge took over her. She left everything behind and even stopped answering Sams calls. All that mattered to her was getting those demons and sending their sorry asses back to hell.
She was on the road to selfdestruction but she didn t care. Years passed until she finally tracked down the demons and killed them.