A VERY BRIEF GUIDE TO RUSSIAN NAMES
Because some strange things happened
In Fiddler on the Roof, there is some significant issues between the Russians and the Jewish people featured. However, there's still some very interesting things happening with the Russians who are named in the play, and it's a fun little subject. This is entirely "the Dramaturg had knowledge and wanted to share".
First of all we have Sasha, which is a totally reasonable male name. It is the diminutive of Aleksandr, and would be used with acquaintances and friends. All is well, going great.
However, then we have Fyedka. Now, Fyedka sounds Russian, it looks Russian, it even is, in fact, Russian. But, no one would introduce themselves with the name "Fyedka" so consistently. It is so diminutive it's pejorative. It comes from the name Fyodor, which the standard "acquaintances and friends" diminutive would be "Fedya". If he was a small child, or his lover was feeling particularly affectionate, he might be "Fyedenka" or "Fyedushka". But, Fyedka is an insult, when handed to someone by their friends. It's intention is usually to demean. Or, when talking about himself, Fyedka could be using it to appear very modest or humble-- which he did boast that he was.
However, with Yiddish diminutives of names, the Slavic ending -ka/ke is sometimes used (opposed to -l and -eleh), and it is entirely possible that this Russian faux pas is due to the Yiddish source material. Either way, It's still strange for someone to introduce themselves with a -ka diminutive, because even in Yiddish, it's indicative of an extremely close and affectionate relationship, and solely a nickname.