[p333347]

Have you talked to this person in order to understand his "serious personality problems" or just basing these on what you hear or observe? You said you brought all the team members, so I assume all of you think alike, which seems obviously different from this person, so the difference in perspective is magnified that much more. I say have an honest discussion. If you have already discussed, share the gist of it with HN so that people can assess things in a fair way to provide useful solution. You also haven't told us how and why he has the most equity. Who knows, he might be an eccentric that not many can understand!