I think I understand the concept - I’ve seen “favourite person”, or FP scattered about all over the place here, but I’d never come across the term before. I’m presuming it means somebody you’re infatuated with in some way, somebody you can’t get enough of. I understand that. 

Do you always have a favourite person? 
Does the person change? How frequently?
If you’re in a relationship, is your partner your favourite person? Can you be in a relationship with somebody, but you’re FP is somebody else?

Curious.