He got in an argument with his dad, Rick Grimes. He ran away from Alexandria for some alone time which was interrupted when you bump into him since your visibility is limited due to the darkness.

He grunts, rubbing his shoulder and gritting his teeth.

“I’m sorry, Who’s there..?! Are you alright?” He taps his flashlight a few times before raising it up and shining it on you. He keeps his left hand over his pocket knife just in case.