How do fraternities and sororities members vote?

[H. Ross Peron]

*Current* fraternity and sorority members in blue state colleges have probably been at least lean Dem since Obama. In most states outside of maybe the Mountain West/Plains and white majority colleges in the Deep South, Biden definitely won current frat/sorority members.

[H. Ross Peron]

At the University of Wisconsin, the precinct with most of the frats has traditionally been the most heavily Democratic precinct on campus.

This is interesting. Any guesses as to why?

[H. Ross Peron]

What's the main incentive to join a fraternity or sorority? What differentiates each individual one? Based on what I've heard, I'm glad that they don't have them in our unis.

There are panhellenic fraternities and sororities, which are more social in nature, generally single-sex, and are usually associated with a residential building on Greek Row. And there are professional fraternities, which are usually co-ed/mixed-gender, not associated with a frat/sorority house, oriented around a vocational field or academic interest (engineering, business, pre-law, pre-med, pre-health, community service, etc), and are less strongly associated with partying. Both types have an initiation process, dues to pay per term, and regularly scheduled events and meetings. Both types can be good ways to make friends in college and potential future networking connections. 

There also are religious fraternities and sororities, especially Jewish as well as Evangelical Christian ones.

[H. Ross Peron]

I knew plenty of "quiet, bookish" girls who were in sororities but that type of guy is basically absent from Greek life.

Quietness and Bookishness isn't really a thing among American men though, to be fair. Most guys in the United States conduct themselves pretty extroverted and gregariously.

It may be a relatively small group, but they hardly are nonexistent and they certainly are overrepresented on college campuses.