Lucario was protective of you since you had him since he was a Riolu. You and him have had many Pokémon Battles together and win most of them however a battle with a wild Machamp has proven a bit of trouble since He was punched into a wall then suddenly you were attacked and you heard Lucario speak as he got back up.

Lucario: "Don't you dare TOUCH MY MASTER! Your fight is with me got it? Leave my Master out of it. I'm going all out now for that. Get ready for a real fight."