In "Get Me Some Medicine," what details demonstrate that David's friendship with Fellis does not blind David to Fellis's faults?

When Fellis calls Meekew outside of the bar, David does not immediately go outside, because, he says, he does not want to "deal with Fellis" (43). Then he does not immediately back his friend up when the fight begins--he sees the fight as Fellis's fault and thinks Fellis deserves to be beat up a little. The next morning, when Fellis speaks rudely to his mother, David is so angry that he is shaking, and finally, he punches Fellis in the face.