Viola is a shooting star that falls into the New World from a different planet. No, seriously—that analogy isn't so far off. She's a settler from the Old World, come to New World for a fresh start. Sadly her ship crashes, killing her parents and leaving her all alone.
Before we dig into Viola's character, though, there's one really important thing to note. So you know how men have the Noise germ and women don't? Since the story is told from Todd's perspective, we get a limited view of Viola. Todd can't read her thoughts—and this confuses him: "And then we don't say nothing for a minute. [But who can tell with a silent girl?]" (21.41). And for us, it keeps Viola a bit of a mystery, too. She's just not as transparent as some other characters thanks to keeping her thoughts to herself.
Now that that's established, though, let's talk about what we do know.
When we first meet Viola, Todd describes that "it's looking back at us like we're gonna kill it. It's hunched down in a little ball, trying to make itself as small as possible" (7.3). Poor, helpless girl. She's ended up in this weird place with Noise, and right away runs into an angry Todd (who refers to her as "it") and his barking dog, Manchee. Welcome to the planet, girl.
Viola isn't just quiet, though—she straight up doesn't react to anything. Like, at all. She holds her cards extremely close. When Todd finds her, he tries to get her to speak and she just stares. Oh, and whacks him on the head: "She's dropped the stick she hit me with and her face is all collapsed in on itself with what she must be feeling from that cut" (7.55). Notice how the expression on her face is the only thing that lets Todd know that she's hurt herself.
This brings us to a really important point. Unlike Todd, whose bark is worse than his bite, Viola's the other way around. She doesn't say a word, but then—when you're not look—she'll bite. And hard. Since Todd and the others can't hear her thoughts, and she keeps her mouth shut, nobody ever sees Viola coming. It's pretty well-played on her part, we think.
So remember how we said that her bite was worse than her bark? Viola may be quiet, but her mind ticks away at a rapid pace. For example, when Todd and Viola get to the bridge (and Todd is freaking out about Viola not being helpful), she gets a brilliant idea. How do we know? Todd describes "Her mouth opens wide, her eyes, too, and suddenly she yanks her bag out front of her and shoves her hand in it" (12.124). Not a word, and before you know it… she's blown up a bridge.
Viola's also has really sharp intuition. When Todd is attacking the Spackle, Viola knows right away that something is wrong, and she tries to tell him to stop: "Can't you see how scared he is?" (25.44) she asks. Of course Todd won't listen, but Viola isn't deterred and helps him see reason, saying, "How many times have you found out that what you've been told isn't true?" (25.86). Viola recognizes the creature's innocence, thinking for herself and basing her assessment on the evidence in front of her, while Todd sticks with past information.
So we've identified that Viola is a lady of action, but let's talk about the fact that she's the one who finally kills Aaron. Hardcore, right? And when Todd asks her why she did it, she says, "I wanted to do it. I wanted to kill him" (42.49). In other words, Viola is someone who trusts her instincts and feelings to the point of action, dealing a deadly blow if that's what they guide her toward.
Importantly, this indicates that Viola has a real driving force inside of her, so thank goodness she finds Todd, who definitely is more of the giving-up type. When Todd asks her if she has any hope in their mission, she responds: "No, I don't, but I'm still going. […] You coming with?" (37.32). This shows the stuff Viola's made of: She doesn't waste time fussing and worrying, so while she may not hold much in the way of hope, she sees that only option is to try.