u/H40ig

I have multiple questions regarding tower of god, fyi it’s one of my best anime series, regardless of some moments I just wished it came out better. I just watched the anime and have 0 knowledge of manga events.
So what I want to know from manga of events after season 2 is how did bam get his power and who taught him and what happened to him before he joined the clan ( all the mysterious events) ?
Please answer me without big spoiling just mild ones.