So I know ~てくる means "to do X and come back" and ~ていく is "to go and do X" But I recently learned that ~てくる can also mean "it started to X" Yes, that's right. They are 補助動詞. Is there some other way ~ていく can be used also then? Yes. (て）いく vs （て）くる? They a bit differ. When you say 慣れていく, it sounds like that you have a will to do it. So it works well when you use "have to": 僕は日本語に慣れていかなくてはならない。 When you say 僕は日本語に慣れてきました。This sounds like you've naturally become so or you're getting like that. I've also seen慣れてきているところ, what does ところ add to the sentence? ところ can mean a state. You're in the state in which you're getting accustomed to something. 5. https://jisho.org/search/%E3%81%A8%E3%81%93%E3%82%8D And do you know the difference just from the context? I'd say yes.