You're confusing partnerships and corporations.

If someone owns 10% of a corporation they are simply a shareholder.

Many people create corporations and refer to themselves and other founding shareholders as 'partners.' This may be the source of the confusion. A partnership (general or limited) is a different kind of business legal structure.

What you may also be thinking of is a directorship. The investor may or may not want to be a director. This would give them a seat at the table for Board of Directors meetings.

In certain states and provinces, directorships lead to some types of personal liabilities.

If they want to be a director, you should make sure they get advice on what they may be exposing themselves to.

Cheers.

David Barnett