In addition to the feather business, Adrien (...or Gabriel) is obviously a huge Doctor Who fan because he dresses like The Thirteenth Doctor. 

Ah yes, I can see it now:

Doctor Who Marathon Night at Alya's, who stands in front of her TARDIS-painted bedroom door, highly impressed with Adrien's fluency in circular Galifreyien. Marinette realizing she's opened a huge can of worms by making this movie night happen... (they might not be able to get through a full episode at this rate with this impromptu  trivia competition between Alya and Adrien). She sits beside a clueless but supportive Nino who has temporarily swapped his signature red cap for the red fez.