Usually when my king dies, almost 80% of my vassals get unhappy/rebellious. And I have to spend enourmous amounts of gold to "bribe" them into happiness.

I have the sucession law which makes the strongest male heir the rightful ruler.
Anyone has any ideas in what provokes such discontent and how one can best avoid it without losing the right to the throne?

Thanks in advance.

I think CK2 has more options considering liege/vassal relationships than the first game (I've never played 2 so I wouldn't know).
In CK1 your relationship with your vassals will gradually increase with time (if you're a good ruler, that is). The trouble is that, as soon as you have a new king, almost 80% of your vassals (from the lowest count to the grandest duke) will become grumpy and suspicious towards you. And the only option the game gives you to appease them is:

a) fill their pockets with gold

b) grant them titles (most of the times you'll only be creating a more powerful rival)

c) wait for them to become so discontent that they'll try to break free from you. Than you can fight them and crush them. But, if such a thing happens, there's a very high risk that you'll provoke a civil war (since all the other grumpy vassals will try to break free as well).

The fact is that your vassals will absolutely adore your king. And then (in the blink of an eye) they will absolutely hate his heir. Which is a bit extreme and not really very realistic IMHO.

Anyway, thanks for the help, Judas.
Any more tips?

Unfortunately, in CK1 you can't transfer vassals (at least that I know of).
You're right about the genetic traits. They've a big social influence. But it seems that the only option you have to "remove" bad vassals is to assassinate them. And stabbing someone in the back is so bad that it's only a desperate measure.

I've been trying to search the web for guides but to no avail. Even though it really is an excellent game it seems that Crusader Kings 1 was a "niche" game for the vast majority of strategy gamers. Most guys I know who claim to love strategy games wouldn't touch the game with a 2-meter stick (I suspect the game was too complex and hard).
Besides the game was released in a time when there was no Steam, so the game came out with few publicity.

It wasn't until CK2 was released on Steam (to much hype of the gaming press) that the gaming world became aware of the series.

Anyway, thanks for the help, Judas.
I'm really starting to suspect that (in CK1 as in real life) when someone starts to dislike you you only have the options to
a) buy them gifts to bribe them

or

b)punch them right in the face. :(

I suppose that what you're saying makes a lot of sense.
I admit I've been neglecting my "children" while attending the royal duties.

Thank you Felgar and Judas for your hints.

Interesting.
In CK 1 they seem to manage quite well on their own, as long as you grant them a good duchy.
In fact, I've been playing the game with the advice thet the good people here have provided and I've been having a great time.

Things have really improved in my dinasty :)

Yes. Like diseases, marriages, etc.
As soon as you give a title to your heir (count, duke, etc) he'll become independant of you and you can't affect his life in any form. He'll choose who to marry or the fate of his kids.

I think that when you change inheritance laws, your popularity with your vassals goes down and you have to earn it back up.

Hover the mouse over the loyalty in the vassal's listing and it tells you if he is gaining or losing loyalty per month, and by how much. If his loyalty is lowish, but he gains loyalty by a few points every month, then don't worry about it. If your vassals are losing loyalty every month, then you do need to do something about it.

It all depends on your strategy though. Do you want the vassal to keep his province, or do you want to take it away from him? If you want him to keep it then you have to see to improving his loyalty. If you want to take it then you can let his loyalty drop and then revoke his title. He refuses and starts a fight, and you win a siege and sue for a peace that gets you the province.

You can also try this with a high loyalty vassal. In that case, there's the possibility that he will just give you the province.