Cross-Campaign Character and Storyline Effects

Okay my question is rather specific since I'm mostly a PvE player. I want to play my assassin throughout all of the campaigns (and focus mostly on him for the time being), but I am wondering what effects this has on the storyline for each campaign because I want to experience everything.

The Factions campaign is obviously not affected, but I am wondering what effects this will have for the Prophecies and Nightfall campaigns. I have played through all of Prophecies once before years ago with a necromancer, so campaign differences is not too big of an issue, but I just made it to the Sunspear Sanctuary (and finished the Wanted! quest) with my dervish only to get him far enough so that when my assassin travels to Nightfall, I can continue where my dervish left off.

Will my assassin have any differences in storyline experience if I continue from where my dervish left off?

Additionally, how will NPCs treat my assassin since I noticed a lot of the NPCs specifically reference my dervish as a sunspear. I'm interested in all differences in experience between using a dervish and using my assassin in Nightfall (and differences between a Prophecies-born character and my assassin in Prophecies).

When your Assassin enters Prophecies, you'll start at Lions Arch and will continue the story of Prophecies from that point onward. You can travel back in the campaign and play the earlier missions if you want to, though. Same goes for Nightfall.

NPC's in Prophecies won't treat you different than any Prophecies born character. However, because you are an Assassin, you won;t be able to buy any skill or armor for that profession in Prophecies, because that game was launched before Factions.

Nightfall was launched after Factions, so there are some skills and armor to be gotten there for an Assassin. Your Assassin will become a Sunspear too.

See also Campaign Travel.

Thanks a lot, Arduin. I was particularly interested in whether or not Nightfall would fix continuity by making my assassin a Sunspear or not.

The main difference in Nightfall is that you won't have all the starter quests in Istan. You will jump into a specific quest for strangers called A Land of Heroes, and then to Consulate Docks mission. From there you play the rest of Nightfall like all others.
Also, remember to do the 2 x 15 attribute point quests on Shing jea island. The similar quests in NF and proph are only available to native characters.

Ah, I had forgotten about the attribute point quests. Thanks for the heads up; I'll keep that in mind.

True, npcs won't treat you any different for a native from the point you enter in the campaign. However if you want to partecipate in the events occourred before your arrival, you will only be able to do cooperative missions and by specifically walking to that outpost, no primary or secondary missions for you in those areas.

Since your character will have been recruited by Kormir, you will be considered a Sunspear. Mention is made in a quest or two of the "foreign leaders" recruited by Kormir during her world travels.