The Japanese care A LOT about whether other people have done them a favor. And if they have given some benefits to you, they care whether you remember it. In the Japanese language, it is very important to mention the benefits you have received from other people. If you forget to do so, you will be regarded as very impolite even if you have used the politest form of the language.
てくれる and てもらう are two sentence structures that allow you to mention what other people have done for you. Let’s look at the examples below: (To make the examples more natural, we use the past tense form てくれた and てもらった. And after verbs that end with ぶ, ぬ and む, they will become でくれる, でもらう, でくれた and でもらった.)
1. 山田さんは私に本を読んでくれた。(Mr Yamada read a book to me.)
After changing 読む to てform and add くれる, the sentence shows us that the action “読む” is a favor done by Mr Yamada. And the recipient of the favor is me.
てくれる can have only one direction, i.e. from other people towards me, so we cannot use it when we are doing somebody a favor. For instance, 私は山田さんに本を読んでくれた is a WRONG sentence. In this case, we need to use てあげる, which will be discussed later in another article. Because てくれる already indicates that the direction of the verb 読む (read) is towards “me”, “私に” is actually redundant. The whole sentence can be rewritten as 山田さんは本を読んでくれた。This shorter version is more natural.
If we further simplify the sentence to 本を読んでくれた, by default it means “you read a book to me”. To say “the book you read to me was interesting” in Japanese, you must say “読んでくれた本はおもしろかったです”. If you just say “読んだ本はおもしろかったです”, the listener will think that you don’t respect the favor he has done for you and become unhappy or angry.
2. 私は山田さんに本を読んでもらった。(Mr Yamada read a book to me.)
The English translation is the same as Example 1. The difference between てくれるand てもらう is that the subject of てくれる sentence is “other people” (i.e. the favor doer), while the subject of てもらう sentence is “me” (i.e. the recipient). In fact, くれる means “give me” and もらう means “I receive”. So the literal translation of the example will be “I receive a book reading service from Mr Yamada”. That said, “読んでくれる” and “読んでもらう” have the exact same meaning, with the former one stressing on “who gives” and the latter on “who receives”. In most situations, they can be used interchangeably, except when you are trying to say “I want you to read a book to me”. In this case, you must use 読んでもらう and change it to 読んでもらいたい. Because it is the recipient who wants something done, the subject of the sentence, even if it is omitted, must be the recipient.
So, to say “the book you read to me was interesting” in Japanese, you can use “読んでもらった本はおもしろかったです”. By using でもらう, you are telling Mr Yamada that you remember the favor he has done you.
Because てくれる and てもらう imply that the action involved is a favor, we can’t use them when somebody do us harm.
てくれる and てもらう have a polite form ていただく, which should be used when talking to people of higher status, e.g. your customers.