てくれる

1. Meaning and Direction
The verb くれる means 'to give' (to me). When attached to the て form of another verb, it means 'someone does something for me.' The direction is generally toward the speaker or the speaker's family/friends. Because the action is typically directed toward the speaker's perspective, the speaker ('I') can never be the subject/giver in this pattern. If you do something for someone else, you must use 〜てあげる instead.

2. Nuance of Gratitude and Sarcasm
This pattern inherently carries a strong nuance of gratitude and appreciation for a beneficial action. Because of this, it is generally not used for negative or unwanted actions in a literal sense. However, native speakers sometimes use it sarcastically to express annoyance at an unwanted action (e.g., 余計なことをしてくれた - 'You did something unnecessary for me'). To express being negatively affected by someone's action in a standard way, you should use the passive form (like 盗まれた) or 〜てしまう.

3. Particle Marking
In this pattern, the entity performing the beneficial action (the giver) is marked with が or は. While this is usually a person, inanimate objects, nature, or concepts can also be the subject if their action benefits the speaker (e.g., 薬（くすり）が痛（いた）みを和（やわ）らげてくれる - 'The medicine eases the pain for me'). The particle for the receiver depends entirely on the main verb. For example, it could be に for indirect objects (like 教える) or を for direct objects (like 助ける). Additionally, the possessive particle の is used when the favor involves the receiver's belongings (e.g., 田中さんが私の荷物を持ってくれた). Because くれる inherently directs the action to the speaker or their in-group, the receiver (私に, 私を, or 私の) is usually omitted.

• 田中さんが教えてくれました。（Tanaka taught me.）
• 田中さんが助けてくれました。（Tanaka helped me.）

4. Formation
Take the て form of any verb and add てくれる (casual) or てくれます (polite).

• 教える（おしえる）→ 教えてくれる (to teach me)
• 手伝う（てつだう）→ 手伝ってくれる (to help me)

5. Making Requests
This pattern is frequently used to make requests. By turning it into a question, you are asking someone to do a favor for you. You can adjust the politeness level:

• 教えてくれる？ (Will you teach me? - Casual)
• 教えてくれない？ (Won't you teach me? - Casual)
• 教えてくれませんか？ (Could you teach me? - Polite)

6. Honorific Form and Commands
When the person doing the favor is of higher social status (like a teacher or boss), use the honorific version 〜てくださる. Note that this verb is irregular in its polite forms: it becomes 〜てくださいました in the past tense. Furthermore, the standard polite request 〜てください ('please do X') is a direct derivation of this honorific form. Similarly, the casual command 〜てくれ is a direct derivation of くれる.

7. Contrast with 〜てもらう
While both patterns describe a favor, the core difference is grammatical focus. With 〜てくれる, the giver is the subject of the sentence (marked by が/は). With 〜てもらう, the receiver is the subject (marked by が/は), and the giver is marked by に.

8. The 'In-Group' and Third-Party Rules
You can use this pattern even if the action isn't for you personally, as long as it benefits someone in your 'circle' (like your child or younger sibling). For example: 'A stranger helped my son' would use 〜てくれる. Generally, you use 〜てあげる when a third party does a favor for another third party (e.g., 'Tanaka helped Suzuki'). However, you can use 〜てくれる for third-party actions if you empathize with or take the psychological perspective of the receiver (e.g., 勇者（ゆうしゃ）がお姫様（おひめさま）を助けてくれた - 'The hero rescued the princess').