Flowers for Algernon
in·ter·lop·er
ˈin(t)ərˌlōpər,ˌin(t)ərˈlōpər/
noun
plural noun: interlopers
a person who becomes involved in a place or situation where they are not wanted or are considered not to belong.
"The War Illustrated." Wikimedia Commons, July 31, 1915, https://upload.wikimedia.org/wikipedia/commons/9/95/Hector_Hugh_Munro.jpg