Year 12 is a higher level of being associated with the ASMS which can only be attained by people who have passed trials being forced upon the ASMS by an external organisation of demonic creatures.
What you need to know about Year 12's
Year 12's are a different class of ASMS students and you can usually tell them apart from other students by their Year 12 jumpers and their ability to access the study rooms (Although other students may be in there from time to time).
Different types of Year 12's
In several cases Year 12's have been known to be very exclusive and will not socialise with "Central Studies kids," however most Year 12's can be sociable (unless you approach them near exam time).