Oblivion - The truth about Gromm's "insanity"

Going back to Oblivion for a bit, the whole situation with Gromm randomly attacking NPCs in Leyawiin was really bothering me, I didn't save and I failed to repeat it at the time, so I decided to go back and try to trigger the bug again.
I tried to remember what made it happen in the first place, and it was the fact that I got sent to jail after trying to complete Sanguine's quest, so I decided to get myself caught stealing, pay the gold, and spawn in front of the castle, and behold, it happened again.
This time, however, we can see that Gromm was actually defending himself from a random Imperial Prison Guard that spawned with him for some reason and that started attacking him for... no real reason.
After killing Gromm the Imperial Guard just left the city to go back to... wherever it is he came from.
Looking at the footage in detail, it seems the NPCs were set to aggro on Groom immediatly, since a couple of them ran away as soon as he spawned.
I wanted to trigger the bug again to get some answers, and instead I got more questions.
Why was Gromm here? Why was the Imperial Prison Guard here? Why was everyone set on killing Gromm?
I don't understand... I don't understand at all.