Renowned Aspie expert Tony Attwood says in his book The Complete Guide to Asperger's Syndrome (thanks to
@Ragnahawk for getting me to buy it) that there is little research about where Aspie special interests originate, but he describes "functions" that might offer clues for you as you search for your next one:
The special interest has several functions:
- To overcome anxiety.
- To provide pleasure.
- To provide relaxation.
- To ensure greater predictability and certainty in life.
- To help understand the physical world.
- To create an alternative world.
- To create a sense of identity.
- To facilitate conversation and indicate intellectual ability.
Look for clues based on this list. If some random topic catches your attention and you become aware that it is starting to help you fill one of these functions (needs), then you might have stumbled across the beginning of your next special interest.