It will be mostly litigation, both criminal and civil. He wants to stick only to the criminal stuff where I plan to do both. I completely agree to the "needing an SJ on the team" as they seem to have excellent organizational skills (something I do not possess), and make pretty good lawyers; but seem to make the best paralegals.
As the the ENTJ, I understand they make great "business people," and I can see this in my friend, but how are they with clients? I feel his "blunt-ness" may be problematic (mine can be too, but I try to use humor to make my point most of the time; as there is nothing more enjoyable than making a point and making people laugh contemporaneoulsy), in the sense that he doesn't sugar-coat anything (ironically, I think he would say the same thing about me).
Also, I suppose I'm trying to figure out where possible power struggles would occur. If we are working on different cases and both have a relative level of autonomy, I figure we'll be ok.
Well first things first - you two will not be running an emotional support clinic, so I wouldn't worry too much about "bluntness". It is an attorney practice after all and most of the people are appreciative of "no bullshit" approach when a lot is at stake. So if you get an emotionally hypersensitive client who might be put off by the whole ENTJ-ness then you probably do not want to deal with that client in the first place. The last thing you want is to be forced to change your whole legal strategy in the middle of the case because your client can't handle the emotional stress of it all.
Having said that, there is a good number of attorneys who are notorious assholes who are so belligerent it's almost comical. They piss off everybody including clients and judges and eventually end up disbarred or sued to the ground, etc. But since you are planning on starting a practice with this ENTJ, I figure you know him long enough to know that he is not one of those folks.
The first and foremost power struggle will be over money, of course. So I hope you guys know exactly how the fees will be split.
Assuming that is taken care of, expect the ENTJ to tell you whats need to be done, and then once he breaks down the tasks, expect him to tell you what to do. ENTJ are generally not micromanagers, but he doesn't like how you did it, expect him to tell you what to do AND how to do it the next time. That in itself isn't so bad (some people do need guidance and reminders), however, if you have a history of being pushed around and have an aversion of being told what do generally, there will likely be trouble.