Up to now my understanding of ~てくる has been very vague. No matter how many explanations I read, in practice my translations always feel uneasy. Here are a few unresolved doubts I have:
From what I understand ~てくる signifies inception or continuation depending on the verb with which it's used. How can I tell which verbs entail which meaning? From what I understand the former meaning is more aligned with changes in state (なってくる, 分かってくる, 太ってくる, etc.), wheres the latter comes in to play with verbs that involve activity (like 押してくる and 運動してくる).
My first question is regarding "state verbs". When てくる (as opposed to other tenses) is attached to words of this class of verbs the meaning is always "start to ~", correct? So "あなた、 いつか私を愛してくる” means "You will come to love me in time"; and "私は義理を感じてくる” translates to "I start to feel a sense of duty"? Can "感じてくる" not mean "continue to feel", that is, without the implication of inception?
My questions concerning "activity verbs" (not really sure of the correct terms here) are much the same. "運動してくる" means "continue to exercise" and "押しこんでくる" means "continue to push in", I think. Is the concept of inception altogether absent? Would it be incorrect to translate those lines as "start to exercise" and 'start to push in" respectively"?
I'm under the impression that when てくる is attached to a verb which indicates a process of change, inception is signified; whereas when it is attached to a verb that doesn't involve change (like 押す or 泣く) the indication is continuation. Could someone better explain the difference between verbs which entail either inception or continuation?
When it comes to verbs which involve change ~てきた is usually translated to English as either has~ or has begun to~, for example, "私は太ってきた" is translated as either "I have begun to get fat" or "I have become fat". To me, those two translations offer two different meanings, yet I often see such translations used interchangeably regarding that verb and others like it. The former translation indicates a change has started and is continuing in the present, right? The latter states a change has completed and the results of said change are persisting in the present. Clearly I'm misunderstanding this kind of usage of ~てきた. Why are these differing translations used seemingly interchangeably?
While these aren't are all my doubts concerning ~てくる, they are the largest. Please help me better understand.