Mentors are generally full-time faculty members with an expertise in the field the student wants to research. As an exception, adjunct faculty or staff could be considered as mentors if they have specific skills and expertise full-time faculty don't have.
Students may ask their mentor for help in narrowing down their topoic. They need guidance in learning the language, practices, and conventions of the discipline.
We expect mentor and student to have regular (in the neighborhood of once per week) meetings to discuss progress and give/recieve feedback. The responsibility to schedule these lies with the student, but the mentor should make themself reasonably available. One or two meetings in a semester or merely reading a penultimate draft is well below expectations.
Because teachers of the capstone class are not necessarily experts in writing pedagogy in general or the student's specific topic in particular, mentors are also asked to provide a suggested letter grade for the thesis/project at the end of the semester.
Faculty mentors reap various benefits from their interactions with Honors students. It is gratifying to see capable and motivated students do great work under one's direction. The student may also be furthering the faculty member's own research. The rewarding relationship often lasts beyond the semester.
It is also the practice of the Honors Program to provide a stipend to good mentors equal to the pay for a one-credit independent study class for one student.