ok, well during Crassius Curio's quests to kill people (Baren Indarys, Reynel Uvrith), immediately after giving me the quest, he told me to "turn around, he's right behind you!", after which i killed them, and immediately finished the quest.

now, I thought this was weird, but gave no thought. then i checked the UESP, and it says you are supposed to go where he tells you to kill them. why did it do this?

Do you have any mods? That's the only reason I can think that would cause it...

It sounds like the Join All Houses mod. I think that it does this.

oh, yes i have that. well that resolves that then. wonder why it does that though?

I believe it resolves issues with building all three strongholds. I think it says something about it in the readme.

Normally you would have to go to the strongholds and kill the people there; however, since "Join all Houses" allows the player to build all the strongholds the people you are supposed to kill show up behind you. This prevents the strongholds from being built until you build them.