Associate status

A person with in a group who is not equal to the rest of the group as he/she separates themselves when the bill or check comes to the tables. He/She pays exactly what what was ordered instead of realizing they were part of an outing (birthday dinner or celebration) and should at least pay a fraction more then what they ordered since you are here for a celebration for another individual. They consider themselves friends but when it comes to paying for others they are alone as they don't buy drinks or rounds of drinks for the rest of the group (pending in the outing of course). They have a separate tap from the rest of the group. Always the first one to look at the tap (bill, check) to separate the math on what they ordered. Exclude other individuals when pertaining to an outing.