What I don't understand is Beevans saying that him joining Quartier Latin, was his worst memory of his life and he shouldn't do it. But if that is the case why did he rejoin Quartier Latin multiple times for short periods (In 1997 before Loi, in 1999 during the preparations of Attentat and in 2014-15 during the 13eme Apotre era) ?

I think he feels that he had unfinished business with the group, then every time he came back he could not get the opportunity he wanted and left heartbroken with a lot of 12 as usual aswell