com·mu·nism
/ˈkämyəˌnizəm/
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noun
a political theory derived from Karl Marx, advocating class war and leading to a society in which all property is publicly owned and each person works and is paid according to their abilities and needs.
Fascism (/ˈfæʃɪzəm/) is a form of far-right, authoritarian ultranationalism characterized by dictatorial power, forcible suppression of opposition, as well as strong regimentation of society and of the economy which came to prominence in early 20th-century Europe.
As you can see, one definition does not relate to cruel dictatorships, and the other does. Communism is not supposed to be cruel and horrible, but Fascism is.
Also, an alliance that symbolically represents Fascism is still terrible, because it means that they are imitating people who committed terrible crimes against humanity.