[Western Crossover] Joker Simulator

Joshua had a secret. Since birth, he'd had a strange System called the [Joker Simulator]. When he first got this weird System, he'd been very interested and looked into it. But most of the pages it showed were grayed out, and the few missions he could do were boring and pointless. After a while, he stopped paying much attention to it.

Then one day, he was late getting home from his part-time job and got mugged. He happened to run into the new bird who'd recently started appearing beside Batman, and the System suddenly went "beep" and activated.

Joshua looked at Robin's retreating figure and the System's screen, unable to believe his eyes. He silently read the mission prompt over again:

Main Mission 1: A Death in the Family

Side Mission 1: Earn Robin's friendship

Side Mission N: Kill Robin with a crowbar

Joshua completed one mission after another out of curiosity. At the very end, he looked down at his brand-new boyfriend lying at his feet, staring at him in shock. He pulled out a crowbar about the size of an ear pick and brought it down hard on Jason's head.

Looking at the fading "crowbar" mark on Jason's forehead, Joshua puffed out his cheeks and said, "Robin, I've killed you now."

The expression on the person on the ground changed from shock to something strangely incomprehensible, and he stammered, "Uh, o-okay?"

A few things to know before reading:

The System isn't serious, so its missions aren't really serious or normal either. The protagonist has a wild imagination. Jason is the pairing, the protagonist is the top, and the story focuses on the Batfamily. Just read it as a comedy. Sorry for the OOC!

Theme: Living happily