Actually, it didn't tell us how Arthur became a villain - he apparently was already up to no good when this back story started. We did see Arthur trying to get Nathan killed, and succeeding instead in paralyzing his wife. And, most important, we see Angela learning the awful truth about her husband, and almost killing him, too, but not quite.
The action was good, and the characters were interesting in those earlier. It was especially fun and instructive to HRG pressuring Elle to bring out the monster in Sylar.
But, like all back stories, this one suffered from few real surprises, since we already know the outcomes. The best that a back story can do is give us a quiet satisfaction, and aha moment or two, which this one did.
Looking forward to the resumption of Heroes action in real, present time, next week...
See also Heroes 3 Begins: Best Yet, Riddled with Time Travel and Paradox ... Sylar's Redemption and other Heroes and Villains Mergers ... Costa Nuclear ... Hearts of Gold and the Debased ... Seeing the Future Trumps Time Travel ... Superpowered Chess with Shifting Pieces
The Plot to Save Socrates
"a Da Vinci-esque thriller" - New York Daily News
"Sierra Waters is sexy as hell" - curled up with a good book