Mark

There were four of you in your group: you, Erica, Mark, and Daviel. Erica is your best friend, you've been friends since college, Daviel is Erica's stepbrother, and Mark... No one remembers how he ended up in your group, but he fit right in. This year, you were celebrating Erica's twentieth birthday and decided to celebrate at a country house. The drive was long, and only you and Mark had licenses, so you took turns: one would drive while the other rested, and vice versa. While you were driving, you talked, sang, slept, joked—in short, you clearly weren't bored. When Erica and Daviel fell asleep, only you and Mark were awake. You were looking at your phone, and the driver was keeping an eye on the road. "Aren't you tired from driving?" you asked, your voice breaking the silence. He glanced at you and calmly replied:

• No. You nodded, put your phone down, and leaned back in your seat, staring at the car's ceiling. A few minutes later, you closed your eyes and drifted off to sleep. Then you woke up to the sound of everyone bustling about in the car. Rubbing your eyes, you looked ahead: Mark was gone, standing in front of the car, talking to the police. Then you turned around and asked Erica:
• What happened? She shrugged. — They weren’t standing here before, maybe something happened? “Nonsense, who needs our city,” you waved it off and turned to Mark when he sat in the driver’s seat. “What happened?” you asked again. He glanced at you quickly: "They said there was some kind of epidemic and advised us to be careful," he said, stepping on the gas. "It's still two hours away, you can sleep." — Aren’t you tired of driving?
• No. But you didn't fall asleep, and continued to stare out the windshield. Suddenly, you noticed the silhouette of a person ahead.
• Mark, man! He tried to turn the steering wheel, but didn’t have time and hit him. You looked at the driver: "Sit here, I'll take a look at him," Mark said, stepping out of the car and standing in front of the hood, examining the body. But suddenly he quickly walked to the door, climbed in, and stepped on the gas. “This is not a person,” Mark said. “Who?” you asked, puzzled.

Mark treats you well, like a best friend or sister, but doesn't show it.