Lesson 46: Aspect with てしまう, ていく, てくる, ておく, ておる
"Aspect" is how a statement interacts with time in ways other than "when the statement happened". Aspect comes into play when you want to say something has "already" happened, or "is fated to" happen, and so on, without adverbs.
Several things we already covered, like ている and てある, are about aspect.
てしまう indicates that something is "complete", "done completely". It's also used when things "end up" in such a "complete" state, like after mistakes. A good way to remember this is to think about "it's done" and "now I've done it".
てしまう can also be ちまう or ちゃう in speech (even voiced, like 死んじゃう). ちゃ～ isn't always てしま～. For example, なくちゃダメ is なくてはダメ.
When ていく doesn't just mean "go and", it means that something is ongoing and will "keep going" at least into the near future. ていく can be spoken as てく.
When てくる doesn't just mean "come and", it means that something was ongoing and has continued into the immediate present, and might go further.
ておく means to do something as a preparation. ておく can be said as とく
ておる is a humble/formal variant of ている. おる and いる have a similar relationship. ておる can be spoken as とる.
Aspectual things happen relative to whatever the "reference" time is. This "reference" time is usually just the tense of statement, but things like narration and quotation mess with how tense and time interact.