In one of my towns this malus is slowly piling up. Fun is: it doesn't reduce automatically over time like the slavery related malus. So how to get rid of that one?

from my experience this happens when you start questioning the loyality of your people by searching everyone in that event... i dont question them anymore and no bad event followed so far.

But that doesn't make sense.

If I whip half of the city population to death (slavery) they forget about it in 30 years.

If I feast from and thereby killing a significant amount of people (1 pop unit) as a vampire they forget about it in 5 years.

If I whip 1 person (as far as the event says he stays alive), they never forget???

I think the design should change here.
If you choose the unhappy person, then the event shouldn't happen again, because people should be afraid to speak against you.
Otherwise, make it temporary, as the OP say, and it can show up again when the malus ended.

That event confuses me greatly.

That event should probably not come up when you play as calabim, it makes sense if you are one of those silly wouldnt-hurt-a-fly civs, not for vampires though. ^^

The AAAARRRRGH malus is one of my own personal demons, as well. It does seem a bit harsh, but then it serves as a way to represent oppression of one's people. The permanency of it is not in line with other such mali, however. I think the existing "We will never forget your cruel oppression!" mechanics would suffice just fine here, unless this is leading up to another chain of as-yet-not-implemented events. Either way, it does deserve strong examination. I'm sure they are seeing all these comments and doing just that. From the results of the past year or so, they seem to design at least somewhat in such a manner.

That event should probably not come up when you play as calabim, it makes sense if you are one of those silly wouldnt-hurt-a-fly civs, not for vampires though. ^^

I thought the Calabim were humans oppressed by a few vampires. There are many depths of oppression....

I thought the Calabim were humans oppressed by a few vampires. There are many depths of oppression....

Precisely. They should be used to random death and torture by now. ;)

I just think that there should be a bonus for using the feasting option. After all, it were a normal feast you would be getting free xp. Some free culture or production in addition to the unhappiness would be nice.