Well... apparently Zahard was a decent fellow when they entered the tower. The journey changed all of the 10 heads somehow it seems.
I agree but at the same time disagree. From what we know, Data Edhuan seems completely different than the real one (from what has been told so far). So it could work for Zahard and the rest as well, but there are still the things Data Edhuan told us about V and Zahard. V was described as kind hearted, he wanted to get closer to the people. Zahard was described as the complete opposite. So in my opinion, Zahard didn't change from "good" to "bad", but from a "bad" to the "worst" person (from what we know so far, of course - you could still be right with your theory about Zahard being some kind of anti hero).
Does it matter?
the Baam we know now is not the same one that was originally born. A god should be living inside Baam's body which is a vessel or something.
Unless I read some bad translation and it was actually resurrecting Baam.
Edit: from webtoon version, Arlene offered the dead body of her son to the god on the outside, so that one day the god will possess it and return to the tower to slay the king.
so this kinda confirm that whatever the case is whether Baam is a bastard child or legitimate, it isn't really 'Baam' but some other god inside his body.
Well, yes, i think it would matter - depends to whom of course, but at least for Bam it would make a huuuge difference and it doesn't really matter who our current Bam really is (God or Bam or both), as long as the God doesn't "take over".
Now he thinks that he should avenge his parents - imagine if he had to kill his own father. In that case it would be his mission to kill his father, that raped his mother and killed him when he was little.
Even if someone told him something like "don't worry, technically it's not you anymore, i still think that this would be a very hard pill to swallow. Again, just to make it clear - i am not sure that it will turn out like this, it's just a possibility (at least at this point)