For pinfu, the pair cannot be a “useful” honor: any of the dragons, your own wind or the round wind.
For example, if I’m 北 and it’s 東 round, I can only keep 南 or 西 as the pair.
You already know this, but British spelling exists! Here’s what you probably don’t know: in British spelling, “practise” is the verb while “practice” is the noun. That is probably why you’ve seen it spelt with a c even in British contexts.