This relationship usually lasts for months or until the person mentored reaches a certain level. Whether informal or formal, both parties need to understand the parameters. The mentor's role is to teach and advise the new employee. The mentor does not interfere with the supervisor or manager's decisions. The new employee, while expected to seek the mentor's advice, particularly on critical issues, is not bound to accept that advice.
Confidentiality is important.
Certain areas may be considered off-limits. The mentor needs to outline these areas at the beginning. Both parties need to make their preferences known at the beginning and reach an acceptable compromise if the preferences are different. Discuss time limits. Discuss time commitments.