What's the difference between くる and やってくる?

Question

Can someone explain the nuance between them? They both mean "come", but I'm unsure of when they are interchangeable. My perception is that `やってくる` seems to put more emphasis on the actual action of coming (compared to the rest of the context, if any) than `くる` by itself. Compare: > * 友達が来ました

*and*
* 友達がやって来ました But there seem to be times when you cannot use them interchangeably. For example： > ○ さぁ、こっちにこい！　→　OK
? さぁ、こっちにやってこい！　→　Sounds unnatural to me Will someone please explain where they do and don't overlap?

Answer 1

やってくる is part of the TE+KURU construct that has kind of become its own thing.

In its most basic form, it would have been "to do something for a period of time" to arrive at the present or to get where the speaker is. Eventually it came to mean "to turn up, come along, come around," as in "Tanaka-san with turn up/come along/come around after the meeting." 会議の後に田中さんがやってきます。

Most of the examples I'm finding seem to place やってくる in a sense that at least implies a process, where as 来る simply shows movement.

会議の後に田中さんがやってきます - Tanaka probably has to drop off materials or pick stuff up before (s)he can come. (S)He may need to show clients out or catch a ride back to the office and so on.

会議の後に田中さんが来ます - Tanaka-san will come after the meeting - it's just mentioning the movement toward the speaker without any implied action or process.

まもなく、新しい年がやってくる - some sort of process took place until the new year could come (the new year took its time)

あらゆる種類の人々が展覧会にやってきた - These people turned up (implied process)