Zack Fair : story 2.

Tragedies of Modeoheim
Zack's next mission sends him to the mountain town of Modeoheim, with Tseng accompanying him once more, as well as several Shin-Ra infantrymen, one of which is Cloud Strife. Their helicopter is shot down by Genesis' troops on the way there, and the team must hike their way across the snow. Zack and Cloud make headway fast. When Zack makes the comment that his companion can at least keep up after seeing how far behind Tseng and the other troops are, they learn that they are both "country boys" and become immediate friends. From this point on, Cloud would begin to accompany Zack on many missions and start to look up to him as a hero and role model.
They eventually come up on a Mako Excavation Facility, that Zack must infiltrate while Tseng and the troops continue on to Modeoheim. Inside, Zack finds Genesis and Dr. Hollander arguing, and Zack confronts Genesis while Hollander squirms away. Eventually defeating the degrading Genesis, Zack watches while the former SOLDIER lets himself fall into the depths of the site. Assuming him dead, Zack hurries after Hollander.
Inside a ruined bath house, Zack finds Hollander and Angeal. He learns here that Angeal's biological father is really Hollander, who used Gillian Hewley as a test subject for Project G. It is also revealed that Angeal did not kill his mother, but she killed herself. Although Hollander refers to him as the perfect soldier, Angeal refuses this title and, accepting the monstrosities of Project G, renames himself as the "perfect monster." He then fuses with several Angeal copy monsters and becomes Angeal Penance.

Zack is forced to fight and kill this creature, obtaining the scar shown in Advent Children. Angeal is left barely alive, and apparently degrading from the wounds. Using his last strength, he hands the Buster Sword to Zack, telling him one final time to remember his dreams and honor to be a true member of SOLDIER. As one of the last 1st Class SOLDIERs, and with the war with Genesis considered over, Zack takes over Angeal's job of being the emotional heart of the organization. He meets another SOLDIER member named Luxiere, who also looks up to him as a role model, and constantly sends Zack mail, he is inspired by Zack's speech to the Shin-Ra troops he commands. Distraught over the death of his mentor and friend, Zack finds comfort in the arms of Aerith, strengthening their relationship to its strongest.

Before the Crisis

At some point between becoming a SOLDIER 1st Class and his final mission, Zack Fair is sent to deal with the insurgency known as AVALANCHE. He is sent to Icicle Inn to defeat an AVALANCHE base along with a player Turk and his SOLDIER freinds, Essai and Sebastian. If the Turk brough is female, Zack will hit on her. Along the way, Essai and Sebastian are kidnapped by AVALANCHE and turned into Ravens, monstrous genetically enhanced humans created by Fuhito to be his personal guard. Zack fights and kills a Raven named Kainyuu, and tries to save the SOLDIERs. However, when he arrives they have been compeletely transformed and must be defeated in battle. After their death, Zack makes a grave for them with each of their swords crossing that appears in his DMW.
Later, Genesis's forces return. With the help of the traitor, Lazard, they break Dr. Hollander out of imprisonment in Junon. Zack is sent here, with a good number of Turks and Shin-Ra Troops to quell the threat of Genesis' copies and the stolen machines of the Shin-Ra company. Hollander escapes with the help of the Genesis copies, but Sephiroth, who appeared late on the scene, forgives him, and gives him leave to go back to Midgar and see Aerith.
Midgar had also been in danger at the same time. Hordes of monsters had appeared, escaped (or perhaps set free, according to Kunsel) from Hojo's lab. One monster in particular, though, had gone to Aerith's church. A single Angeal copy that was protecting Aerith from the monsters and Shin-Ra's confused machines until Zack arrived. Although never fully stated, it is believed that this single copy is all that is left of Angeal's will on the Planet, and is perhaps being controlled by Angeal from the Lifestream.
Before Zack leaves on his next mission, he and Aerith build a wagon so that she can sell flowers throughout Midgar. Zack has to stop selling early, though, as he is called away to investigate the Mako Reactor at Nibelheim. Trusting Tseng to look after her, he, Sephiroth, Cloud, and two other Shin-Ra troops head to Nibelheim, Cloud's hometown.