ENFperator, Rick and CuriousSoul, thanks!

The person I'm thinking of is Robert F. (Bobby) Kennedy, JFK's brother. I have little doubt that he was dominant, and ISFj would appear to be the most obvious choice, but when watching or reading interviews with him, I get more of an INFj impression than ISFj -- there are other things as well.

He and Lyndon Johnson (ESTp I now think) couldn't, by all and their own accounts, stand each other at gut level. To me it seems like conflict, but it could conceivably also be supervision.

By the way, he was called "ruthless", "self-righteous" and "mean" by many who knew him personally, also friends and family. His father said of him, approvingly, "Bobby's my boy. When he hates you, you stay hated".

I'll think about this further -- I see the problems with INFj, of course.