There are several qualities that are not optional for the close friend of a leader to possess. Two of the most important are a pure heart (right motivation) and someone who always speaks well of them. I got this from the greatest leadership book every written, by the way. I'm about to quote from it. The truth is that leaders are so consumed with a plethora of details, they don't have time to worry all the time about whether the folks close to them are there for the right reasons, or have their back.
Proverbs 22:11 says, God loves the pure-hearted and well-spoken; good leaders also delight in their friendship." Proverbs 22:11 (MSG)
What does well spoken mean? It speaks of positive, loyal conversation.
The NLT puts it this way: "Whoever loves a pure heart and gracious speech will have the king as a friend." A person that Proverbs 22 speaks of will not only HAVE the king (leader) as a friend, but a person who is faithful with these qualities also KEEPS the king (leader) as a friend.
If you are a person God has chosen to be a close friend to a leader, these qualities are not optional if you want to have a lasting relationship.