I usually find one of the brothers exploring the plains in the Reach north of Markath. They mostly clutter the landscape with arrows making your savegame bigger and tell me I should join them. Ha! I'd rather join the Silver-drift hunters had it been possible

Okay, this is weird, but Aela and I were out in the boonies somewhere not far from Markarth when i saw some guy running with a 2H sword, followed by a woman in studded armor, followed by a sabre cat. The guy would get to some spot, pause, turn round and run back the other way around a little hill and out of sight. The woman and the cat did the same thing! Back and forth, back and forth, like they were in a Benny Hill show. Finally I one-shotted the cat, and other two stopped running and sheathed their weapons. It was Vilkas and Ria. Funny thing was, I haven't seen either at Jorrvaskr in a long, long time.

Ria killed a bear today. Did you kill anything?

Twice with my character who's the harbinger.

First time: The 4 recruits fighting a frost troll and setting a snow bear onto me, plus Farkas tagging slowly behind. I followed Farkas for a while, but he just ran in a wide circle, before suddenly sheathing his sword and moving back towards whereever he may have come from.

Second time: Having just left Bthardamz and finishing off the last few Afflicted who were roaming around outside of it, I was approached by a slowly walking Ria and Vilkas. I almost shot them, because they looked like bandits or something.

Haha same thing happened to me! My second character is married to Vilkas, and once I took his brother Farkas with me on a quest, and when I arrived at a small town a dragon appeared. In that chaos, I thought "something looks familiar", and when I killed the dragon I saw Vilkas saying "Is it really dead then?" I approached him and he said "It's good to see you again, dear". Stalking me, are you my love??

Also, my first character married Farkas, and once I found him outside Winterhold walking with the mead-addicted Companion and the elf. I ran up to him and he said "Yes love?". What do you mean, "yes love?"? You're supposed to be at home, preparing me a hot meal for when I come back, not wander here with your friends!!!!

About dozen times in all my games. Before, during and after doing the Companions questline. Always fighting random wildlife. Very odd; I wonder if they've been accidentally mixed into the random spawn tables somehow? After you meet them they always beeline it for the Jorrvaskr...

There's one time when first heading to Whiterun and there's a couple of Companions killing a giant, but there's been a couple of times I've spotted one or two of them. They may have been who my main character got into an inadvertant tussle with on a mountain trail while heading to meet The Greybeards for the first time. Lydia ended up in a never-ending fight with one of them. She just keep beating him till he yielded, then he'd attack her again. Ended up leaving her to continue my quest and met back up with her at Dragonreach later.

They can get into friendly fire incidents with your followers. That happened to me and I had to run to the next cell and fast travel to "summon" my follower.

Bumped into them a few times. And like others said, its always before joining. They almost always end up trying to attack me though. Like when you have a brawl and someone walks into your fist and you get a bounty.

I find them fighting bears all the time. I think Temba Wide-Arm has been bulk buying Companions contracts.

once. I finished the quest line and then i saw skjor fighting a troll. now he can give me quests =)