Have a random question instead:
Two guys (unrelated) call each other 'aniki' and 'aibou' and it's really fscking hot. In fic:
I should go on using aniki and aibou because it retains the hot of the situation.
I should use 'older brother' and 'partner' because using Japanese is always, always bad.
It's a moot question because everybody who reads KRK will know exactly what you're getting at.
As i do not read in your cracked out fandom, I don't give a hooping funt.