Author's Note: Unbeta'd. First time writing Teen Wolf. This was actually requested by someone on tumblr when I was browsing the sterek tag and I'm not sure who but nonetheless I hope you all like it.

Disclaimer: Teen Wolf is property of MTV.

Erica enters the warehouse quietly, hoping catch Derek unaware. She hesitates slightly as she remembers his words after the kiss. Shaking her head, she continues down the stairs and towards the train car slowly, making little noise.

She lifts her head up as she hears voices and hides quickly behind a nearby pillar. She hears footsteps from the other entrance and leans against the pillar, slowing down her heart all the while hoping that Derek doesn't notice.

She peeks out and sees Derek leading Stiles to the train car. He has his arms wrapped around Stiles' waist and is nuzzling Stiles' neck.

"Derek," moans Stiles, turning around and leaning up to kiss him.

Derek smiles into the kiss and Erica can see that it's even more intense than the one that she shared with him. He picks up Stiles, causing the other to wrap his legs around Derek's waist.

Derek breaks the kiss and looks up at the train car before striding towards a nearby pillar and leaning Stiles against it.

Erica gulps and watches as Stiles grasps at Derek's shoulders while moaning loudly.

She turns away and leans back against the pillar. She didn't except Derek to be with Stiles or that he would reject her advances. He was different when he turned her but now she could see that it was an act. Stiles is the one he wants.

She peeks out again and watches as Derek grinds against Stiles. He captures Stiles' lips in a bruising kiss then nuzzles the side of his neck.

She knows that he's scent marking him, it's what she wants to do. Erica leans back against the pillar and proceeds to slide down to sit. She keeps her heartbeat steady and silently prays that they either get into the train car or stop making out soon.

After what seemed like an hour, Erica hears Stiles say, "Not here."

She peeks out and sees Stiles push Derek away and grabs his hand before walking to the train car. Derek pulls Stiles closer and briefly kisses him before nudging him to the train car. They both watch Stiles enter the train car and Erica lets out the breath she didn't realize she was holding.

Derek turns and before she can hide behind the pillar, he sees her. "This is the last time that you do this. Leave, now," he said with a serious tone.

She scrambles up and hears him growl as she tries to walk towards him. She hesitates then turns around and exits the warehouse, leaving the two lovers alone. Outside, she looks up and smiles as thinks about going to the school on Monday. It'll give her a chance to tease Stiles about what she saw today.