Steve-
You speak Russian. You met Steve through Nat-she's your sister. You never spoke any other language, even English.
Tony-
You speak French. He always thought it was adorable, when you called him Monsieur.
Thor-
You spoke Spanish. He always thought it was funny when you rolled your rs.
Clint-
You spoke German. You weren't with HYDRA, though.
Bruce-
You spoke a lot of languages. Norwegian being one of them.
Natasha-
You spoke Russian, with her. You can talk crap about people without them knowing. LOLLLL
Loki-
You spoke Chinese. Also, Loki helped you try and speak Asgardian (is that even a language lol)
Bucky-
You speak Swedish. You tried to teach him, but it didn't work out.
Pietro-
You're Mute-
He learned sign language so you didn't have to go though the trouble of writing on paper all the time.
You Speak A Different Language-
You speak Czech, and he can sort of understand you.
Wanda-
You speak Polish. She can't understand you, but she uses her magic to translate for the both of you.