Comment by Kaypo on Our Companionship - Chapter 23

@Kaypo  the only thing i can think of is that they meant brother in law — so his "girlfriends" brother 
but to be fair im just as confused as you💀

@Kaypo  Idk...but in India, it's a thing to call your friends partner like that. Like I call my bestie's gf as bhabhi(sister in law) and the female friend's bf as Jiju(brother in law)...I am sure they meant it in that sense.