“Nomura, explaining Cloud’s situation in the film, has said “Cloud tried to lead his life positively after the end of FF7 but he cracked… The sin which Cloud thinks he owns is not anyone’s fault in particular. It is something Cloud has to overcome by himself.” Nojima said the theme of the story is one of redemption; “If you want to be forgiven, you have to take the hard path in life.” Cloud, in choosing to fight against Sephiroth once again, is finally “given healing and forgiveness.“ Nomura concluded, “Cloud seems to be a weak guy. Generally, heroes are strong, cool and don’t have any weaknesses… It’s through redemption from his friends and having children to protect that he becomes stronger.” Cloud’s feelings of guilt and regret for not being able to save Zack and Aerith are symbolized by a grey wolf that appears in scenes in which Cloud thinks about them. The wolf disappears at the film’s conclusion as Cloud comes to terms with his feelings.One of the staff’s favorite scenes was where Cloud smiles in an embarrassing way towards Tifa. Nomura liked it as there was almost no dialogue, and the expression on his face communicated his emotions to the viewer. Composer Nobuo Uematsu commented “It sounds cool!”, considering the fact that gamers who have finished Final Fantasy VII would find it hard to imagine how Cloud smiles. Upon reading that scene in the script, Uematsu was inspired to write the score.“
I got this from here. Wiki cited it as ”Tetsuya Nomura (Director) (April 25, 2006). Final Fantasy VII Advent Children Distance: The Making of Advent Children (DVD). Square Enix.“