I feel like the fact that dude is just referred to as "Lacile's brother!" over and over again is an important detail. Like maybe this flashback is a false memory or something.
We're just gonna refer to everybody in relating to Lacile from now on aren't we. Like I wonder if they'll fight Lacile's adoptive sister's father or Lacile's adoptive future sister's future father in the end?
Yeah, the author gives names to random cities that the reader won't even see so I think lacile's brother not being named could have a deeper meaning here