I created a story board that shows Baudouin & Fabiola's friendships with other royals
Akihito and Michiko were/are good friends, and they give credit to Baudouin as the one who did the most to make it possible for them to be together. They were separated with Michiko being sent to Europe. Akihito reached out to Baudouin, who not only spoke to Hirohito about the importance of the right spouse for a sovereign. He also took all of Akihito's letters to Michiko in Europe after no Japanese diplomats would help.
Juan Carlos and Sofia (with whom they vacationed virtually every summer). Baudouin learned Spanish and was very happy during his vacations in Spain.
He was close to Juliana and Beatrix and Baudouin pretty much grew up together.
He was also very friendly with QEII.
Harald of Norway was his cousin, so there are a lot of pics of them with Olav and their family.
He was quite close to his sister, Josephine-Charlotte and their children were close nieces/nephews, particularly Margaretha with Fabiola. And, of course the Luxembourg and Belgium families are all related.
I'm on another royal board where they were just stumped as to the political or etiquette reasons why QEII would attend Baudouin's funeral. It's because they were FRIENDS, and she looked up to him. Their stories were similar in many ways about taking on responsibility early in life and their strict adherence to duty and having a wild sibling.
He seemed to be very friendly with the last Shah, and Fabiola remains close to Empress Farah Pahlavi.
I also get a distinct feeling that he was on very friendly terms with Haile Selassie.
He was a remarkable man and Fabiola is remarkable - both for their openness and friendly personalities.