Not really sure but looks like the AI tries to give fiefs to the same person that has other fiefs in the area. That is what has happened to me once we took over the Aserai I pretty much got the bulk of their castles and towns in that area. Now if they capture something else far away no I never get the option.
Somewhere in this forum is a thread, where someone presented the factors used in the code. Here is what i remember from the top of my head:
- Distance between the new fief and your closest two fiefs matter. The closer, the better for you. If you only have one, it will only use this one for calculating the distance. If you don't have a fief, the game will treat you as if you have a fief right next to the new one. (This is why clans without fiefs often get the very remote castles deep inside enemy territory.)
- Clan strength relative to the amount of fiefs owned matters, i.e. number and quality of the troups in your party, your other clan parties (i think) and the garrisons relative to the amount of your fiefs. (I think, it also factors in the prosperity of the owned fiefs. Can't remember how though.)
- Clan Rank matters. The higher, the better.
- The Kind and the Conquerer get a bonus.
These rules apply to every clan in the kingdom. Also, this was for a previous version of the game, so there might have been tweaks. And also probably some minor stuff i don't remember.
So, in conclusion, to increase your odds of getting a fief / be included in the vote for ownership:
- Conquer new fiefs close to your previous ones
- Increase / improve your garrisons and personal army
- Increase your Clan Rank (if you are not rank 6 already. Should be max, i think).
- Be the Conquerer
Edit:
i sieged and won the same castle 5 TIMES in a 1-hour period playing, never being a nominee for ownership.
You could estimate the distance from this castle to your holdings (just by eyeballing) and compare it with the clans, who usually appear in the votes for this castle. I would reckon, the holdings of the other clans are closer and hence they score higher in the priority for this castle.
Within the timeframe of 1 hour, there propably wouldn't be many changes in the variables influencing who ends up on the vote. Since you were not in the right position to be in the vote for this specific castle the first time, you consequently were not in the right position the next four times.