Hi, there:
I have a question about the term " invest".
When I saw a movie trailer. I heard that the actress said"-----emotional moment hits you so hard because you are
in Em and Dexter-----."
I know like "invest money" but I didn't get the term "invest" well in the sentence.
Could you please clarify it for me?
Thanks a lot!
This is a fairly recent use of "invest," I think (and one that has, in my opinion, become overused, but that's not your question 
).
People now say that they are "invested" in someone or something when they've devoted a lot of time, energy or emotion to it and, as a result, care a lot about it. It is an analogy to financial investment. You might say that our time, energy and emotion are our non-financial capital, and, when we "invest" it in something, that thing becomes more important to us because of the investment.
In this case, the actress is saying that the audience has spent time with Em and Dexter and gotten to know them. As a result, they have grown to care about them. When whatever happens to them happens, it "hits [the audience] hard" because of this caring. If the characters had been unimportant to the story, the audience would not be so "invested" in them and wouldn't be so affected by their fate.
