Is it a problem if father son are joking horsing around and son accidentally causes a bruise to father? If it is a problem how does one do teshuva?
Is a scratch the same as a bruise? I am referring to when the scratch just caused a red mark. No actual bleeding
The only bruises that are included in the severe prohibition of hitting a parent is if it causes them to bleed, or a bruise that causes a black and blue mark. However since it only caused a red mark and no bleeding, etc. it would not be included in this prohibition. Aside from this he did not intend to scratch him, and it would be considered aino miskaven. Nevertheless it would be a good idea that your father should say that he mochel.
Y:D 141-2, Minchas Yitzchok 1-27(3), Gesher Hachaim 2-1 (1), Poskim.