I ship Cloud and Aerith because Aerith is the first person in the game Cloud cares for besides himself. In fact, Cloud cares for Aerith despite not fully being himself. This fact doesn't diminish their relationship, but proves how strong it actually is.
Before I go on, this is an important quote:
"After developing his personality by using Zack's memory as a base, Cloud still maintained the part of coolness even though Zack had cheerful characteristics. The part of Cloud's coolness that keeps him away from the surroundings and the part of his asserting "no interests" all have nothing to do with the influence of Jenova cells. They belong to th