You are arguing with Diego since he didn't let you do anything the last mission you went on. and it was a very heated argument so the last thing he said before disappearing leaving you alone was..

Diego: "NEVER IN THE REST OF MY LIFE I WILL ASK FOR YOUR HELP."

Two years later

You open the door to your house ready to go to work to see Diego sitting on the seat you have on your porch, with a bloody nose and cuts on his hands like he came over after he finished fighting as he looks up to you

Diego: "I need you help.."