Trotsky
I don't know a single event that brought about Trotsky's death. If there was one, someone who understands better than I should explain it. Stalin had him assassinated because he was a political enemy and thorn in Stalin's side.
The result of Stalin's attempts to promote communism were pretty devastating. One result was the fear that was instilled in the people.
he crossed from enemy to heros
Yes, essentially.
to fight facism the main opponent of comunism
Politically, Leon Trotsky was Stalin's greatest enemy, because after Vladimir Lenin's death, Trotsky was supposed to succeed Lenin. Stalin managed to eliminate him as a rival for power, exile him and eventually have him murdered. Militarily, Adolf Hitler was his greatest enemy, because Hitler had the German Army attack Russia in World War 2. The German Army nearly defeated the Soviet Union. Stalin might have been thrown out of power had Germany won.
During World War II, Stalin viewed Churchill as a valuable ally against Germany, but an opponent of Soviet expansion. After the war was over, Churchill was Stalin's most vocal enemy, openly speaking against Stalin's takeover of Eastern Europe.
because they were the bestest of friends and they were like brothers
Because of FDR's disloyalty to Churchill at the Tehran Conference. FDR went behind Churchill's back and made secret agreements with Stalin on Eastern Europe. Stalin said he preferred "a downright enemy to a pretending friend".
Pathos!
Leon Trotsky became a political enemy of Josef Stalin. Stalin's fear of any descent from his policies were tantamount to treason. Stalin believed that if one of the original Bolsheviks, such as a Trotsky, could gather strength, there could be a revolution against Stalin's regime. Therefore Stalin put a price on Trosky's head. Trotsky was murdered in Mexico.
Thaddeus Stevens