How to indirectly add an antagonist's POV to my story?

Hey r/writing,

I need some advice for developing my antagonist through multiple POV’s. My main issue is that I need to add the antagonist’s POV into the book so that the audience can understand his motivations and thought process. However for most of the book, the identity of the antagonist is a secret. So I need a way to add the antagonist’s perspective without tipping off his identity to the readers.

**Here is some context into the story and my problem:**

My story focuses on two protagonists who are brothers (Brother 1 and Brother 2). In the beginning of the story they are separated from one another and go on to live vastly different lives. The chapters alternate between their two perspectives.

For the first half of the book the audience doesn’t know who the antagonist is. But later in the story, I want my audience to suspect that a certain character (who later is revealed to be the antagonist) is manipulating Brother 1. The audience only sees this character through the POV of Brother 1, whom he is manipulating. Because Brother 1 is oblivious to the manipulation, the clues have to be incredibly subtle. Something that only an attentive and observational reader can pick up on. My goal at this point in the story is to have my readers suspect that something is fishy about the antagonist, and that he is manipulating one of the brothers. However, I want it to be totally unclear as to what the antagonist’s motivations are.

I want to flesh out the antagonist’s character (since he’s the most interesting character in the story) but I want to do so indirectly. So I’m going to use Brother 2 as a device to reveal things about the antagonist without the audience’s immediate knowledge. Basically, Brother 2 will hear folktales and hearsay regarding the antagonist. Keep in mind Brother 2 has no idea who the antagonist is, and doesn’t even know he exists. So the audience and Brother 2 shouldn’t immediately relate this info to the antagonist, they should just seem like unrelated stories. These tales and urban legends will provide Brother 2 with skewed clues about what the antagonist is (he turns out to be a supernatural being). But because this information is gathered from word of mouth and folktales, the information is horribly inconsistent, biased, and has inaccuracies.

So I have the actions of the antagonist being displayed in Brother 1’s perspective. I have some slightly inaccurate information that provides insight into the antagonist’s capabilities, history, reputation, and nature being displayed in Brother 2’s perspective. But the audience still has no idea what the antagonist’s motivations are. Until the very end of the book I want the certainty of this character as the antagonist to be unknown, and I want his motivations to be unclear. I feel that only by adding the antagonist’s POV can I properly have the audience understand his motives. But I need to find a way of doing this that doesn’t reveal his identity, and that doesn’t seem too cliché. I think that it would seem way too obvious if I blatantly added a chapter in the antagonist’s POV. The last thing I want the audience to think is, “Who is this new character? Why is he important and how is this relevant to the story now?” The only possible idea I could think of is that Brother 2 finds a diary that belonged to the antagonist. But this seems incredibly unrealistic and cliché to me. Perhaps the antagonist could tell Brother 1 stories about his life that provide clues regarding his motives. But this might be too obvious as well…

**TL;DR:** I need to indirectly add the perspective of my antagonist so that the audience can later connect the dots and understand his motives. But I have to do so in a way that isn’t immediately picked up on and that doesn’t reveal the antagonist’s identity.