Here are two situations which aren't really
that weird but still quite odd.
First, I was walking from Skingrad to Anvil (not using fast travel for the sake of roleplaying) and I was shocked to find a man in Blades armor on the road fighting a bandit. It was Baurus! I helped him kill the bandit, and then he took off, running about the same speed as I could so I couldn't catch up to him to talk to him. I followed him all the way to Kvatch, where he ran past the open gate (I hadn't progressed the main quest at all) and proceeded into the city, into the chapel, and stopped next to Martin. What a hero.
Spoiler I later realized this happened because I had used the console to progress the main quest past a certain point in order to get an item early on, as I didn't intend to do the main quest on that character. Still pretty interesting how Baurus' AI took over, but Martin's was still keeping him in Kvatch.
Second, today, I went to Pell's Gate and saw Glarthir standing there. For this, I have no explanation. I'm still stumped as to why he was there, so far away from Skingrad. I didn't think his script allowed him to leave Skingrad
ever, especially since I had started his quest and it was night time, he should have been waiting outside the chapel for me to continue the quest. He just shooed me away when I talked to him.