Who is Ruda from Under a Cruel Star: A Life in Prague 1941-1968 and what is their importance?

Ruda is an acquaintance of Kovály though they were apparently not very close before the war. Ruda's wartime job is not described other than to say it keeps him away from home for all but a few days each year. Ruda is connected with the resistance and, when informed of Kovály's plight, immediately offers his usually-vacant apartment as a temporary hiding place. He then arranges for Kovály to contact local resistance elements and thereby ensures her ultimate survival. Unlike many other associates, Ruda is selfless and brave.