This seems to happen to a number of players at some point. You fast travel somewhere and arrive accompanied by... what? Recently I've had a number of fellow travelers appear on arrival with my mage.

For example, I fast traveled to Windhelm Stables and had two wolves and a bandit with me. Non-hostile, no reactions from anybody else. At this point a dragon attacked. One of the wolves died, but the other and the bandit helped kill the dragon. After that they traveled anywhere I went, but only if I used fast travel. I even nicknamed them, "Smokey and the Bandit." I forget how I lost the wolf, but the bandit died at the fort west of Whiterun. Apparently when I attacked his buddies it snapped him out of his daydreaming and he attacked me.

A day ago I decided I wanted some Forsworn gear for enchanting, so I went to Karthspire Camp. Got all I needed, but when I fast traveled two non-hostile Forsworn came with me. Again, the first time they showed up, a dragon attacked. One Forsworn died in the attack, but the other survived, and still shows up whenever I fast travel.

What has arrived with you when you fast travel?

Sounds buggy as Hell.

I've never had anybody fast travel with me who shouldn't have, but maybe that's because I don't fast travel often?

During the Stormcloak quests, I borrowed a horse from the camp and rode it. After that, it fast traveled everywhere I went, but then would turn and walk off like it was heading back to camp.

Lol, I'll have to try fast traveling a few times again just to see this happen, before they patch it up. ^^

Never had non-hostile fast-travel hitchhikers... Usually some necromancers or dremoras just spawn in and kill everyone forcing me to reload my save.

That's awesome. I've never experienced anything like that and I Fast Travel almost all the time.

Ulfric Stormcloak, Gen. Tullius, Lokir, a few imperial soldiers, Legate Rikke, Gunjar, Ralof, Hadvar, Ingrid, Torolf, Vilod, Matlara, And haming. Practically all the people in helgen...

there was a thread abut this a while ago. so at least you know its not just you.

http://www.gamesas.com/topic/1354617-massive-spawn-inside-whiterun/
http://www.gamesas.com/topic/1360567-restless-draugr-suddenly-appears/page__p__20526278__hl__fast%20travel__fromsearch__1#entry20526278

I was fixing up a save for someone, fast traveled to Riften to check something, and there were three bandit marauders and a frost troll tearing the market apart. They caught me so off guard I just activated God Mode and turned collision off and flew into the sky until the guards downed them.

This happen to me only one time so far becuase I very rarly used fast travel. When I fast travel to Morthal, I have a "Wounded" Frost Spider and two Falmers. They were all hostile to me but I had town guards help me out, It was one of my biggest WTF moment.

The only things I have found so far is hired thugs or dragons.

Looks like things are back to normal for my mage. There's still the one Forsworn loitering outside my mage's cabin, who will assist in attacking Thalmor or other roadside rodents. However, nobody else is hitching a ride. I think this started when Steam couldn't connect to its server, and messed up the save file data.

Sometimes a dead hagraven(?).

I've gotten Draugr most often, but also Falmer, and once Nihume--the spider from Markarth and with a bunch of Falmer. A group of necromancers, conjurors and elemental mages all turned up at the Throat of the World a couple of days ago. (And that stupid dragon did nothing help, either. Just sat there on his wall and watched.)

It happens so often that I always look around as soon as I arrive somewhere after fast traveling....

Mostly non-hostile wolves. They don't stop howling, so I always kill them. Had a dead hagraven once. But, that's all.

Haha. I did that too. I only pressed the botton to get on the horse by accident and got off straight away, but the horse was with me the entire game. It would even show up outside some dungeons when I exited.

A funny bug happened when I got killed many times outside Fort Katsav by the mages. I would respawn exiting Stillborn Cave and the horse would spring into the air and go flying for miles.

Nothing like this has happened to me, however, if I walk into a shop after talking to an NPC, the NPC follows me inside for a split-second.

I have a good company when fast travel: two bandits, marauder-mage, one bandit-like npc and... Esbern!!! Than quick fight and Esbern go to the... I don't know... maybe to greybeards.

Some time ago bandit-like npc - Thalmor Sorcerer who reanimated and then killed. This npc are piecefull and stand in spawn point without any movement.

Well, the Forsworn that was hanging around my house miraculously appeared when I FT'd back to Karthspire, his old stomping ground. I thought that was that, but he came with me to High Hrothgar. A fus-roh-dah later and problem solved.