Year one: School and teachers
Year two: Hogwarts and the chamber of secrets.
Years three: Ron’s trip to Egypt. Which got Hermione talking about her fascination with all things ancient Egypt. Which lead to Ron telling her the stories Bill told him about his work there. Which got Hermione talking about the muggle interpretation of the obvious magic used in ancient Egypt. Which got Ron asking about muggle interpretation of other magical things. Which lead to Hermione ask about the way Wizards view muggle technology and things of that sort. Which lead Ron to ask how muggle technology worked because its something his dad was always interested in. Which had Hermione asking why Ron’s dad was so interested in muggle things? Which lead to a conversation about growing up in the Weasley’s household. Which lead to a conversation about growing up in the Granger household.
This didn’t happen all in one sitting, but in bits and pieces throughout the year when Harry wasn’t around. They would be sitting in the common room when Harry was with Lupin and Hermione would randomly go,
“Exactly what type of cure breaker is your brother?”
“I started thinking about how I only knew the muggle version of ancent Egypt and it had me wondering about the wizarding worlds version so..”
“You went to the library”
“Yes, and read there were two types of curse breakers, one for cursed objects and the ones that break curses placed on muggle archeologist who stumble into wizards tombs. Which is your brother?”
“The object one, but sometimes the curse is linked to an object so they have to work togeather. Bill told me about this one bloke…”
Year three when the crashes started developing. They found one thing that they were both fascinated by that slowing broke off into more personal conversations where they began to have a deeper understanding and like of each other.
Year four: Harry and the tournament. That whole year was about Harry and who was out to get him.
Year Five: They talked about their fears. How they feard for Harry, their families, the wizarding world, each other. Umbrage, Dumbledore, the ministry of magic.
Year six: They didn’t talk much year six.
Would be years seven: Very similar to years five but more urgent and littered with “If I don’t make it,” “Don’t you dare think like that,” Wonderings if the people they care about are Ok. And we know they talking about Harry not knowing what he was doing.