I had already pulled the pin on a grenade come up yo crouch which literary device is most clearly shown in this excerpt?

The literary device most clearly shown in this excerpt is irony.

Here's why:

* Situational Irony: The situation is ironic because pulling the pin on a grenade is an extremely dangerous act, and one would expect the person to run away, not crouch. The action of crouching seems counterintuitive and even more dangerous in this context.

Let me know if you'd like to explore other possible literary devices!