Otto Klopp is Alek's piloting teacher, and the best master of mechaniks in Austria-Hungary. Like Volger, he has given up everything to keep Alek safe from his enemies, but unlike Volger, he's not a nobleman. But while Klopp isn't Volger's social equal, they are partners in the business of keeping Alek safe.
Klopp is like the nice teacher everyone wishes they had, the one who encourages you to always be your best and tells you that failing is part of learning. However, don't let that trick you into thinking Klopp's a softie. He plays good cop to Volger's bad cop, but that doesn't mean he's going to let anything distract him from keeping Alek safe, even if this means going against what Alek himself wants:
Alek switched back to Clanker-talk, ordering Klopp to disconnect the walker from the sledge. I was odd how many words in German were almost the same as in English, once you'd got your ear in. For once, though, Alek wasn't getting his way. The old man folded his arms, and kept saying nein and nicht, which any dafty could tell were Clanker for "no." (31.9)
Klopp might not be a prince, but there's no question that he outranks Alek.