Ein smelled of lies because he was an undercover cop at the time, who have to lie to stay undercover. I am baffled as to why Diesel did not tip Yanek off, if he is supposedly so protective of him. Did he feel something for Ein back then and was not aware of it at the time, or...?
Diesel may have "felt" safe then, but in reality he wasn't. He even admitted that staying with Yanek would have been the end of him.
Chapter 19

Then why, WHY did u run away with Ein?! WHY wen u felt safe with Yanek did u choose EIN who smelled of LIES?! I am royally baffled and quite confused as to if I still would like to ship Diesel with Ein...(ein I still love u tho u mah boi)