Currently playing as a norse buddhist ruler in Wales/Northern England. As I converted from Norse(Åsatru) to Buddhism several generations ago, I think I am considered casteless. Is it possible for my character to somehow join a caste? I know it's not such a big deal when you're playing as a Buddhist, but the small bonus to prestige/wealth/karma looks nice. I looked around on the wiki a bit, and I noticed there was an event that allowed you to join the warrior caste for a hefty fee, although I think it's only available to Hindus.
Is it somehow possible for my casteless Buddhist king to join a caste?
Convert to Hinduism for a generation, change caste, and then go back to Buddhism.
Hindus have a decision to change to Kshatriya. You either need to be Brahmin and spend some karma/piety, or if you are casteless or Vaishya, you need to spend a bunch of gold (like 100 times your monthly income), which can be halved if you have Learning of 12+. However, since the gold cost is based on monthly income, you just need to run a deficit and you can convert for cheap.
In a recent game, my monthly income was 1000+ ducats a month, so the cost to convert was 100,000. So I went over my demesne limit for a few months and my monthly income plummeted to -400 a month and I was able to convert for a mere 100 ducats.
So as a Hindu, convert to Kshatriya and have kids, and then next generation, convert back to Buddhism.