I'm confused, if Sasha and Milo are brothers then why did they use different last names? Or did I not read that right?
That's a good catch, I wanted to talk about that anyway. So I assume you're referring to the names I tag them with sometimes, Zacharias von Wolfenstedt and Matthis von Halberg. Matthis and Zacharias are probably as close to birth names as you'll get considering phonetic shifts. They're the names they used the longest, primarily during the time in the Army, and still use in more serious or intimate settings. (Sasha still calls Milo "Matti" sometimes, which nobody else is allowed to do, even Attila.)
If you know how last names worked back then, you also know they weren't really fixed, just an easy identifier and could change if the community thought it necessary.
Both their last names are place monikers, pointing to a place of origin and on the surface it does not make sense why that would be different if they're brothers. The thing is, they're not blood-related and even if they were they look so different people wouldn't have believed it.
Both of them used the moniker von Halberg when they joined their first crusade and after they'd been turned. Halberg is a peak in the Saar region of Germany, which is the place Milo usually claimed he comes from (he really doesn't know for sure). Sasha was actually given the name von Wolfenstedt by others. Wolfenstedt translates to "wolf's place" or "lair". After being turned, Sasha very quickly made a name for himself by being a ruthless and effective strategist as well as being a skilled fighter.
People said he was so good at being a werewolf because he was in fact raised by wolves. Which was absolutely a racist jab, but Sasha's approach was always that no tool is too low as long as it was effective. And also that people leave you alone if they're sufficiently scared of you. By the time the army splintered, Zacharias von Wolfenstedt was more of a bogeyman than a real person. In modern day, Sasha and Milo mostly use the same last name, because it makes paperwork easier.
Thank you for the question!