The Seven Deadly Sins Episode 6

How did they all become sins in the first place?

Meliodas

Why is he this strong, I guess I'm use to characters in anime to go through some kind of trial and revelation to obtain the power they have. I do remember him saying something about knowing magic or possibly knowing magic. How did he become a captain

Elizabeth

She have shown be very loyal to the group. She seems to really be proving herself. I kind of feel bad for her because she can't fight in this episode.

Ban

Something is wrong with this guy, he looks evil after all he is the Fox sin of Greed. Ban's demeanor reminds me a bit of Dante in the anime of Devil May Cry. So far he been getting stabbed and he just not dying, so i'm assuming his healing factor is more like wolverine or deadpool. I've only seen him get stabbed twice. So far he is cool, I like him. Also why is he so strong.

Diane

I still she has warmed up to Elizabeth and we won't see so much of her jealous side. I'm sure we'll see more of her fighting. Seem like Elizabeth have touched her heart.

Melionas and Ban

I think this is friendly rivary, It's good to see their not mad at each other. I really want to know who is strong between them two.