I was ambling along a road and in the distance a woman and a man spotted me and ran towards me and started to attack like crazy. I tried to defend and failed. I managed to get them down to almost 0 health and they'd fall to the ground but bounce back up in full health. The woman's name I noted was Ria; the man's was V-something. I checked them on the Wiki and Ria is a Companion and I guess V is, too. But why would they attack me. They aren't like Guards, are they? Awhile back a Winterhold guard attacked me and wanted me to pay a 2,800 bounty but I wasn't having that. But is that the reason Ria's upset with me? I reloaded a number of times and was never able to conquer them. Their health always rebounded no matter how I pounded them. So I ended up having to go way around them.

Vilkas is also a Companion, yeah. They do react to the bounty system for whatever reason, so if you have any price on your head, they act like the guards and try to kill you on sight. I don't think they're supposed to do that, but it never got fixed.

Some of the quest they send you on are to find criminals and kill them, so it doesn't surprise me at all that they attack you if you have a price on your head.

To OP, why don't you just get that bounty taken care of and stop un-necessary killing and stealing.

Vilkas is a persistent one. he chased my forsworn girl across most of the Reach. he followed me everywhere including into interior cells. Eventually I got far enough away that I could fast travel without being prompted "You can not fast travel while being pursued." I ended up having to pay my bounty. They attacked me on sight in Whiterun at Jorrvaskr even though my bounty was in the Reach...

Of course later my forsworn girl Valeria spent the night with Vilkas. She found him charming and persistent

Stole his blade, if memory serves.

Yeah I was wondering why he'd be chasing your girl ...

The Companions take up bounty quests. I've done a few.

Do I have to go to jail to pay my bounty? I don't want to lose all my weapons, and other things.