Len was walking to the kitchen. Suddenly, a hand shot out from nowhere and covered his mouth. He was pulled backwards, and the other mysterious hand covered his eyes. That's when he felt the cloth under his nose. The hands weren't necessary as Len faded into unconsciousness.

...

The stranger looked around. He and the stranger were alone. He didn't actually know the guy. He just knew that he was one of his many targets, and he would provide easy access to the rest of the crew.

He pulled something out of his pocket. It was a bottle, and it contained something very rare: a potion called Turning. It made made everyone an enemy and poisoned every moment he had ever had with the person, so that way he could say the most painful thing. Sometimes, it hurt so bad that people tried to commit suicide.

Except the person who had injected/feed him the potion.

It was always fun to use.

...

Len woke feeling like crap. "What the hell?" he asked the man leaning off to the side. He didn't know the man, but for some reason, he trusted him.

"What's your name?" he asked before the guy could answer the first question. The guy thought for a moment before answering. "Bob," he said. "And yours?" Len had to think. What was his name again? "Leonard, but you can call me Len," he said, although he couldn't tell you why if he tried. 

...

'Bob' smirked. His plan was working perfectly so far. Now, all he had to do was murder everyone else on the ship. Simple.

...

Barry was bored. So, he naturally went on a search for his favorite entertainer: Leonard Snart.

But, he couldn't find him.

Suddenly, Len walk right by him.

"Hello?" Barry questioned. Len turned to face him. "Yes?" he asked. "I'm bored," Barry said. Len looked at him. "So?" he replied. "Can we hookup?" Barry asked. "Sure, Barry," Len said. He and Barry walked over to Len's room.

Then Len had Gideon make the room soundproof.

Then he turned to face Barry. "Before we start, I have to say a few things," he started. Barry nodded. "Of course. Say whatever you need to say."

...

He would deeply regret saying that.

...

Little did Barry know, Len was distracting him. He was the most powerful on the ship, so Len had figured in order for Bob to invade it, Barry would need to be busy.

This was how he would keep Barry busy.

...

https://youtu.be/nyEC2h1Jyys

Note: This is how I'm modeling this talk. Except, Barry is Karofsky, and Len is Sebastian. 

...

"Well, Barry. I want to make sure you know somethings," Len said, looking Barry right in the eye.

Barry nodded again. "Go on," he said.

"Well, I'm only doing this because I like to hookup, and you're the only one who will. I don't hookup with girls and no men on here are gay. 

"Another thing. You're really bad. Have you never practiced? Are you that unattractive? 'Cause I certainly would understand. I'm cold, what is considered the opposite of hot, but even I'm hotter than you."

Barry gasped, tears filling his eyes.

"I don't like you, Barry. At all. If anything, I hate you. Your a jerk. Selfish. That's why you'll never be a hero. Because you couldn't be selfish if you wanted to."

Barry looked at him, shock clear. This was actually what he thought about on a daily basis. Was it true?

"That's also why The Reverse-Flash targeted you. Because you deserved your Mother to die. She didn't deserve to die, but you deserved to live without a mother. Your Dad shouldn't have gotten blamed, but I bet he was happy to be rid of you. You must have been such a disappointment. Same with your Mother. Bet she was happy to be rid of you."

Barry couldn't believe everything he was hearing. Len really did hate him.

He felt tears fall down his cheeks. He looked around for an escape, but the doors were locked, no one would be able to hear him, and Len obviously wasn't going to let him go.

"Now, I'm going to give you what you deserve."

Len stripped, and then he looked Barry up and down. "Undress," he commanded. Barry gulped. "N-n-no," he stuttered. Len looked at him. "You deserve it. Besides, you wanted to. So, undress," Len said. 

Barry closed his eyes. He did deserve this. But he didn't want it. He didn't know what to do. 

Then Len made the choice for him. He pulled down Barry's pants and his boxers. Barry started to hyperventilate. It was happening again. He was defenseless. He deserved this.

...

The whole time, Len kept whispering in his ear. "You deserve this," or "Let it happen, Barry." 

Barry felt completely powerless. "Help," he whispered brokenly under his breath. Then he was slapped. "Don't. Say. Anything," Len said angrily. Barry nodded.

After what seemed like forever, it was over. Barry looked down when he noticed the lack of body heat. He saw Len pulling up his pants, and he sped over to his. He had his on and saw Snart smirk. "In a rush, huh?" he asked. Barry growled. It was a warning. He never wanted to see Snart again. 

...

Note: When Barry thinks of Len in an enduring way, he thinks of him as Len. When he thinks of him as the enemy, he thinks of him as Snart. Just wanted to clear that up if anyone was confused.

Also, this has a part 2, possibly part 3.