I met a mercenary walking on the road from Solitude. He said he was hired and on his way to do something, but would not say what. He was wearing Elven armor and I did not have any in my inventory. I wanted some really badly, but did not kill him. Anyone know what he might have been hired to do? Just curious.

it's random but you can persuade or bribe him into telling you where he was going and what he was doing to update your map

I ran into one of those near Darkwater Crossing not long ago. Intimidating her prompted her to go hostile, but she didn't have any note or anything on her saying where she was going.

I came across one going to Riften, I met her just past the mill. I persuaded her to tell me where she was going. She updated my map but still have no idea what she was on about. Anyone have a clue?

I think it's just to get a new place to explore on the map mostly.

I've encountered several, all with the same conversations. They mark something on your map, but never say WHAT it is - and since my map has up to a dozen
places that I've heard about but not visited yet I have no way to figure out which one(s) are new. Well, I could do a detailed before and after comparison of the map,
but it's not worth the bother. My only concern is whether these missions are on a time sensitive basis. Doesn't seem so, yet.