The Bishop of Rome ( term Pope was not always used) was considered the First amoung equals.
There is alot into church history and please understand that there was no cell phones, or no phones, no postage service, you could not fax and there was not even a printed bible.
So with all of that the churches of the east and west were not able to communicate on a regular basis and each Bishop of the Council was the head authority over his group. One did not rule over the other. Society and customs and even culture differented between east and west. And with that came many problems.
I would advice you read not only a book about the split from the Catholic view point, read also a book from the Orthodox view point. They do not fully agree on exactly how it happened.
I do agree that basicly the Orthodox Bishops would not go under the rule of the Bishop of Rome. If you read what the Orthodox writers havd to say you will at least understand what your friend is being taught.
I compaire it to reading about WWII from a Japanese history book, a German history book, a french history book or a US history book, they will not fully agree on all aspects of the war.
It is like the statue of Benedict Arnold, to the English he was a hero, to America he was a tratior.
