Legacy Characters in a 10 Year Franchise

by Xenos , Shores of Time, Tuesday, February 26, 2013, 21:17 (4087 days ago) @ Stephen Laughlin

Will players be able to attack each other in the open?

From the IGN article:

Naturally, of course, there will also be a fully featured competitive multiplayer mode, though neither Jones nor anyone else from Bungie was willing to offer even a hint about any details just yet. Well, other than the fact that you won’t be forced to engage in player-vs.-player combat unless you explicitly desire to.

So I think that would rule out attacking each other in the open.