What is the difference between が and を when using verbs?

Question

In this anime-esque example, which is correct?:

1. 私はあなたが殺す
2. 私はあなたを殺す

And why? Because I’ve heard it used with number • 2 • を (wo), but other verbs seem to always use が, for example: 「私はエミリアが好きです」 Is 好き a noun in this context?

Answer 1

Both sentences are perfectly correct, but the meanings are totally different. Let's start with 殺す because it's a rather simple transitive verb which takes one subject and one object. Conclusion first, those two sentences translate to:

1. 私はあなたが殺す = You will kill me. / It's you who will kill me.
2. 私はあなたを殺す = I will kill you.

In both sentences, 私 is marked with は. But Sentence 1 says "you kill me" and Sentence 2 says "I kill you". Why? Let's review the basic functions of は, が and を.

• は is a topic marker. It can mark both a subject and an object depending on what you want to "focus" in the sentence. It works by replacing が/を.
  • What is the subject of this sentence? Is it the book (mentioned) or the author (who is not mentioned)?
  • What's the difference between wa (は) and ga (が)?
• が is a subject marker. It marks the subject of a verb.
• を is an object marker. It marks the object of a transitive verb.

There are many exceptions, but these should be enough as a starter. In Sentence 1, the subject is clearly あなた because it's unequivocally marked with が. So 私 will be interpreted as the object of 殺す. In Sentence 2, the object is あなた because it's unequivocally marked with を. 私 will be interpreted as the subject of 殺す.

---

Regarding 私はエミリアが好きです, there is no verb in the first place because 好き is something called a na-adjective. For details, see: 私は猫が好き and 猫は私が好き