Zack and Aqua met at the Olympus Coliseum. Aqua was talking with Hercules and Phil and learned that Zack fought against Terra in the tournament. He explained that Hades was exploiting him and causing him to be covered in darkness until Terra saved him. The two later fought in a match and Aqua won. Zack was still cheerful after their match and undaunted by his loss. However, he got upset when Hades appears and asked Aqua to get revenge for him and Terra.
Aqua fought against Hades in a match while Zack cheered for her in the stands. Hades brought an Ice Colossus and claimed that having a back-up was allowed so Zack immediately came to Aqua's aid. However, she told him to let her take care of the battle alone. Aqua ended up winning and the two left the coliseum together. Afterwards, Zack asked her on a date in order to celebrate her victory. Aqua immediately became flustered and explained that she was on a journey. Zack then promised that they would go on a date after he became a true hero and left. Hercules then arrived that noticed that Aqua was blushing.
Zaqua is a rather popular Kingdom Hearts ship. It is not quite as popular as Terraqua is still a very popular ship, especially for one involving Aqua. While Zack had Aerith as a love interest in the Final Fantasy series, the two are not known to have even met in the Kingdom Hearts series so many fans feel that it still works out. Many were amused when Zack decided that he and Aqua would go out on a date and found to be obvious that Aqua may have liked him a little.