What is "舎弟" supposed to mean in this context?


Speaker A tells speaker B that he feels like he's seen her before, speaker B
responds with:

> あんたアレでしよ？哲也兄がこっちで舎弟にしたっていう

And speaker A replies:

> 哲也兄！ ？ っていうか俺そういう扱いなの！？舎弟って、俺あのハゲに兄貴分らしい事何一つされてないんですけど！？

What I'm confused about is why does speaker A call Tetsuya "哲也兄" - Tetsuya nii
when the 兄 suffix is used for older brothers but then she says Tetsuya is her
younger brother "舎弟", there's something I'm misunderstanding here but I can't
pinpoint what. My best guess is that I'm probably misinterpreting 舎弟, which
could have another meaning that's not in a dictionary and doesn't literally
mean younger brother?

I would be grateful if someone could point out and explain where I'm going
wrong, thank you!




You seem to have missed several points.

  * Despite what jisho.org says, AFAIK 舎弟 is never used to refer to one's blood-related younger brother in modern Japanese. Here 舎弟 means someone's subordinate/disciple/pupil/follower/etc. It's mainly regarded as gangster jargon today, although it may be more like a casual [弟分](http://jisho.org/word/%E5%BC%9F%E5%88%86) in this context.
  * You seem to have failed to recognize the [`～にする` construction](https://japanese.stackexchange.com/a/32807/5010). (～を)舎弟にする means "to take on someone as a disciple".
  * Speaker A said "哲也兄!?", but that does not mean he _calls_ Tetsuya that way. Speaker A just repeated in a surprised tone what speaker B said.

My translation attempt (although not literal):

> B: あんたアレでしよ？ 哲也兄がこっちで舎弟にしたっていう  
>  B: So, you're the person Tetsuya-nii took on as a disciple here.  
>  B: Oh, I think I know you. Tetsuya-nii said he took on you as a disciple in
> this place.
>
> A: 哲也兄!?  
>  A: (You said) Tetsuya- _nii_!? (i.e., Wow, is Tetsuya your older brother?)
>
> A: っていうか俺そういう扱いなの!?  
>  A: Wait, is that the way I'm supposed to be treated!? (i.e., Do you mean
> someone said I am a disciple of Tetsuya?)
>
> A:
> 舎弟って、俺あのハゲに[兄貴分](http://jisho.org/word/%E5%85%84%E8%B2%B4%E5%88%86)らしい事何一つされてないんですけど!?  
>  A: What the heck is "disciple"? That bald bastard did nothing for me like a
> leader!

