Most textbooks explain that 行く and 来る can be generally translated to English as to go and to come, except when the perspectives/locations of the speaker and the person performing the movement are different. To include those situations, a better rule would be:
- use 行く when the movement is away from the speaker (or from A to B when the speaker is at an altogether different place C, as in "At what time are you going to the movies tonight?"),
- use 来る for movements toward the speaker (or in the same direction as the speaker, as in "Come with me!").
This is all clear, but I can come up with several other situations that either are not covered by this framework, or perhaps even violate it.
First off, if you simply look up 来る in Jisho, the first example sentence is:
１０時までに来ます。(I'll come by 10.)
This seemingly violates the above rule, as the movement is in the direction away from the speaker. The way I explain it to myself is that here we have a strong accent on arriving at the destination, since we're specifying the time. 行く simply wouldn't work, as "I'll go by 10" has a different meaning. Is this correct or am I missing something?
Apart from that, the above rules don't cover situations where there is no speaker whatsoever and we have a narration instead, like in books. Consider, for example:
Harry Potter is going to Hogwarts next week. / Harry Potter is coming to Hogwarts next week.
In English, these sound fairly similar. What would these sentences look like in Japanese? I feel like both should be acceptable:
ハリーポッターは来週ホグワーツに行きます。 / ハリーポッターは来週ホグワーツに来ます。
Is there an implied difference in meaning between these two sentences? I can't really tell since I'm a beginner and haven't got enough practice.
Thanks a lot!