Phin Asu is a very powerful Jedi and has tried to join the Council many times, but much like Qui Gonn he disobeys the code from time to time so he was regretfully denied each time. The last time Phin disobeyed the council was when he helped Biss Hiyu attack Palpatine's home, he was then told as a punishment he could never serve as a member of the council. The Jedi Master sensed the conflict Anakin was having, (who he had become close to) but like his former Padawan Qui Gonn he blinded himself to it due to his beleif.
Asu is a Talz from the planet of Ord Mantell, he was taken to be trained as a Jedi at the age of two but due to his father's anger the Council almost denied him.