What is a god to a non-believer?

Nightmares

Izaya woke up panting. He was sweating. He felt something wet on his face. Tears? "Damn it!"

He had experienced the effect of the venom: nightmares. Ones specifically targeted for him. It was infuriating. They had pushed him to the point of crying in his sleep. "Damn you, Yui."

This would certainly take effect on his everyday behavior. It'll be worse if his enemies noticed it. Izaya remembered what Yui had told him. "Those nightmares will continue until you learn to face your feelings and come to terms with them."

"Come to terms with my feelings huh? Easier said than done."

Turns out she was right: he was afraid. Afraid of being hurt despite being surrounded by people who can help. That was the reason he chose to love all of humanity. Izaya used that as a method of protection, to let it all wash over him than taking in any of it. And that woman might break apart that method, revealing the fragile content inside. 

From that day, being attacked by gangs and mafia men became common for Yui. As usual, they were either killed, turned to stone, or found brain-dead (soulless). The same happened when they took the people she cared for as hostages. All this infuriated Izaya, complimented by nightmares that kept getting worse. Unlike most nightmares, these didn't let him wake up until morning with tears pouring from his eyes. Thankfully, he was able to hide his sorrow. Though it kept getting harder every day. 

Still, he kept pestering and talking to Yui. In even more so than before. Izaya kept an even closer eye on her than before, looking for some sort of weakness. That was one of the greatest challenges because she never let her guard down nor displayed hardly any emotions. Then he thought of her family, he knew her father wanted her back very much and her sisters were rather jealous of her. He smirked as he sat down on his desk and began typing on his computer. Then, he clicked send. All he had to do now was wait and what how his lovely humans handled the situation. Well, humans plus monster. This wasn't the first game he had put Yui in, but now she was put against the one thing she seemed to loathe more him. He burst out laughing. "Hahahahahaha!"

Namie looked at him with her usual annoyed expression. "You're insane, you know that."

"Oh I know," he replied as he got up and made his way to his game board. He picked up the queen chess piece and moved it one square. "Let's see how you fare, my little Yu-chan."

While this was happening, Yui was on her way home from some Russia Sushi. It was her day off and she had just finished her lunch. Suddenly, she heard a chipper voice behind her. "Hey look! It's that girl we saw in his file!"

She turned around and saw two similar-looking girls. It was clear they were related, most likely twins. They wore similar jackets and skirts, except with reversed colors (black skirt, yellow jacket, yellow skirt, black jacket). One had glasses and a braid with a big smile on her face. The other had no glasses and short hair. The one with glasses began talking. "We saw a photo of you in one of our older brother's files." 

Yui narrowed her eyes. "What do you mean?"

The same one continued. "Well, you see . . ."

Flashback

Mairu and Kururi walked into Izaya's office. "Hey, big brother, you here!" shouted Mairu.

"No one's here," added Kururi.

"Well then let's leave the file the guys asked us to bring on his desk and leave."

As the twins made their way to their brother's desk, they noticed another file open on his desk. They exchanged glances and began looking through the file. "Yui Nakanishi . . ." uttered Kururi.