The Vice President
The Vice President's primary task is presiding over the Senate. Although he doesn't have much of a say in the decision, he does vote in the case of a tie. If something were to happen to the President, the Vice President is first in line to take over office. 25% of Vice Presidents have become President through presidential succession. In the past, the Vice President didn't have much of a role, but the President has been more reliant on the VP in recent years. The Vice President can serve as a confident to the President, depending on their relationship. Most of the Vice President's roles are informal.
The First Lady
Though the First Lady does not technically have any political role, they play a crucial role in the White House. They have been given the title of "Hostess of the White House" because they plan and attend presidential events at the White House. Many times, the First Lady is seen as a fashion trendsetter, like Michelle Obama. They may also use the position to become advocate's and create programs that they are passionate about. The First Lady often has a much higher approval rating than the President.