My grandfather was an INTJ. He was probably my only close family member who really understood me, and was one of my best friends until he died when I was 19.
I had a very close INTJ friend for about 8 years, but we would occasionally disagree and finally she wrote me off as a friend. I have tried to make up with her, but she will have none of it.
I think the whole shared Ni thing can be both a bond and a challenge in relationships between INFJ's and INTJ's.