As for Paladins and Crusaders: A long time ago, the Paladins headed west under the command of Rakkis seeking conquest, a historic march which ultimately ended in the founding of Westmarch. Meanwhile, the Crusaders – an elite group of fighters who rallied under a different Zakarum leader – headed east on a secret mission to search for a way to cleanse their faith of the perceived taint left behind by Mephisto. Unlike the Paladins, the Crusaders have never been corrupted, and in their journeys abroad have honed new skills and talents that set them apart on the battlefield.
To put it a different way, think of the Crusaders as the “veterans of the veterans.” They take zealotry to an entirely new level, finding comfort and strength in their unshakable confidence in their cause. Their only goal is to find a way to save their faith; any other objectives will fall to the wayside should it ever threaten to impede their quest. Whereas the Paladin might meddle in a town’s affairs — settling disputes, converting new followers, burning some witches — and then move on, the Crusader, despite brandishing a similar level of intimidation, would quietly enter the town, ask a few questions, restock their supplies, and then depart, leaving little more than confusion in their wake. (To give you perhaps a more relatable image, if you were put a Crusader in space, he’d probably be a lot of like Hicks in Aliens. Very experienced, a little easy going on the surface, but doesn’t fool around when stuff hits the fan.)
More specific details on the Crusader will, naturally, be covered in Reaper of Souls (as well as in Acts I-V). However, if you really dig that sort of lore, definitely keep an eye out for the Book of Tyreal. You can expect to find some good juicy historical tidbits on several of the orders, the Crusader’s included.
I’m looking forward to playing a new Crusader through the content and learning about the character through all the dialogue and interactions with the NPCs and followers. Like most players, I found that aspect of Diablo 3’s story pretty enjoyable, partially due to the complete absence of lecturing holographic pumpkinheads. The Crusader is going to be interesting also for the “same story, new character” aspect; just seeing how a different class reacts to the story events of Acts 1-4 that we already know so well.
Update: Nevalistis added more answers in a subsequent post:
So Crusaders were formed around the time of Rakkis or after the events of Diablo 2?
The former. They were founded at about the same time Rakkis set out to conquer the west. The leader of the Crusaders sensed Mephisto’s taint in the Zakarum faith, though it had not yet been uncovered, and independently/secretly founded and sent the Crusaders off on their mission. They have remained a mostly secretive sect of the Zakarum faith until now. Crusaders tend to travel alone, occasionally with a ward or apprentice, and rarely interact with one another or the public as a unit. It’s part of the reason they’ve remained unnoticed for so long.
I think in terms of lore the Crusader will be fitted like he was the original cast of heroes, not only joining in act V but another hero that searched for the Fallen Star, so he will be a Nephalem.
The Crusader has been integrated into all five Acts. You’ll learn their motivation behind pursuing the Falling Star in New Tristram, and the NPCs surrounding them will question and interact with their presence as well. The Crusader’s story should look and feel as if they were there from the start, and we hope you enjoy getting to re-explore Sanctuary from a different point of view.