it is maybe faaaaaaaaaaar off but:
in S1E11 we got to know that "He is Mar" - just take it as it is written - and forget about everything else.
Bruno Heller's dad was a German Jew - so Bruno Heller probably speaks Jiddish. If i am not veeeerrryyy wrong "mar" means "Mr". in Jiddish. I am a native German speaker and translating "Mister" into German - there is only ONE possibility - it means "Herr" which you can use to adress men or LORD. As we learnt from the show - you never stray too far away from your environment when creating an alias.
So my guess is Stiles (reducing everything to the basics!) even if I can not shake off the feeling that it is Bertram!
