Aerith and the first thing he doe's is to start flirting with her. Aerith plays along, because she misses Zack (Having being gone for four years and died a few days prior to this) and Cloud reminds her of him
In the game, Aerith clearly states that her relationship with Zack was in the past and that they were NOT serious. From FFVII directly:
Cloud: "You were...serious?"
Aerith: "No. But I liked him for awhile."
Cloud: "I probably knew him. What was his name?"
Aerith: "It doesn't really matter."
Here's another thing.
Aerith did not act all that concerned when she found out that Zack had been missing for 5 years and was possibly dead. Here's a piece of dialogue from Gongaga:
Aerith: "What a shock.... I didn't know Zack was from this town."
Cloud: "You know him?"
Aerith: "Didn't I tell you? He was my first love."
Cloud: "......"
Aerith: "Zack.... SOLDIER First Class. Same as Cloud."
Cloud: "Strange, there aren't that many who make First Class, but I've never heard of him."
Aerith: "That's all right. It's all in the past now. I was just worried because I heard he's been missing."
Cloud: "Missing?"
Aerith: "I think it was 5 years ago. He went out on a job, and never came back." "He loved women, a real lady's man. He probably found someone else."
Aerith and Zack weren't madly in love with each other. It's more of a puppy/platonic love. By the end of Crisis Core, Aerith moves on and says a line of dialogue that I forgot. AND DUG UP:
Aerith: Are you doing well? Where are you? It's been 4 years. This will be the 89th letter I've written but I will not send out any more. I hope that you receive this last letter. Zack! The flowers are selling very well. It makes everyone smile. It's all thanks to you. Aerith. (Aerith's 89th and final letter to Zack, Crisis Core)
Zack falls to the Church of the Slum during his mission and ends up meeting the girl Aerith, who's trimming flowers. They both feel contented simply with each other's company; it's a platonic love. They think these kinds of happy days will last forever, but.... (Crisis Core Ultimania, Zack's profile)
They attract to each other by mutual feelings similar to friendship, because they're both juvenile, if you call it love... (Crisis Core Ultimania)
Cloud and Aerith didn't flirt with each other. Aerith pretty much approached him and she just eased easily with Cloud. You'll notice that Cloud is a lot more open to Aerith because of her personality through body language. And Aerith was the one who actually wants to know more about Cloud.
Regardless that Cloud took something from Zack, that would be his confidence and memory for being a SOLDIER, Cloud's body language and gestures are ALL HIS. He did not "become" Zack. In fact, Zack and Cloud are exact opposites. Zack was a "ladies man", very outgoing and friendly. You can even see it in the hidden scenes of Nibleheim Mansion Lab. Cloud is introverted and cold.
In fact, here you go:
Due to the influence of the Jenova cells implanted in his body he acted out a false persona, but with the support of his friends he regains his true self and grows as a person. (FFVII 10th Anniversary Ultimania)
This statement says nothing about Cloud becoming an entirely different person. He merely acted out a fake facade of being a cool, strong, SOLDIER guy to cover up his own inner weaknesses.
(This is related to what I meant in the other thread where Cloud is a representation of what is expected from the male society. A man being in SOLDIER is the highest honor and the only thing you can do to impress Ms. Tifa because being a good guy and saving you from the falling bridge in Nibleheim mountains isn't enough.~)
Cloud idolized Zack and in the Nibleheim memory scene, he's the shinra mook soldier that Zack was teaching some poses. He may have promised a dying Zack that he would live out both their lives but Cloud acts nothing like Zack. Cloud imitates Zack's cocky attitude as a First Class SOLDIER and even learns some of Zack's moves and gestures. However, that is where the similarities end. Cloud is as cold and condescending toward others as Zack was carefree and warm. They're not the same.
Also see this line from Aerith's date scene:
Aerith: "First off, it
bothered me how you looked exactly alike. Two completely different people, but look exactly the same. The way you walk, gesture... I think I must have seen him again, in you...
But you're different. Things are different..."
She's bothered. It means bewildered, confused and/or annoyed. If she really likes 'Cloud for being Zack' she wouldn't use this word. And she quickly interjects, but you are different, meaning he's not acting like Zack.
In the novel Maiden of the Planet, which could be considered Canon because they're known for their other novel works, it is revealed that Aerith and Cloud do love each other.
Aerith tells Zack that his "bad point" was that he was a flirt. Thee fact that he wasn't "simplistic and awkward like Cloud". And so Aerith is stating she prefers Cloud's simplistic, awkward behavior to Zack's flirty, womanizing behavior. And to finally destroy this 'Aerith likes Cloud because he's Zack,' "She loved him [Cloud] much more than her first love." You can't get much clearer than that!
Also other stuff:
Even though Aerith perceived that Cloud had lost sight of his true self, she still has great affection for him. (FFVII 10th Anniversary
Ultimania, Aerith's profile)
Although in the beginning, Aerith felt close to Cloud because he behaves like Zack, her interest in Cloud himself grows and is attracted
to him. (FFVII Ultimania Omega, p. 31)
"I'm looking for you."... "So you won't have a breakdown."- what Aerith told Cloud reveals many deep meanings. Aerith detected that
the present Cloud is not the real him during their encounters. She knows it because of her mysterious, inherent ability. (FFVII
Ultimania Omega, p. 29)
When Aerith thinks of Cloud and Zack's similarities, she sees that the present Cloud is not the real Cloud. Her meaningful lines like,
"I'm searching for you" and "I want to meet you" all mean that she has discovered the existence of the real Cloud, although he's not
aware of it himself. (FFVII Ultimania Omega, p. 31)
I'm sleepy but anyway.