Nell Mescal describes herself as “chronically online.” So chronically online that she regularly breaks one of the internet’s cardinal rules and searches for her own name on Twitter.

It occasionally turns up some funny stuff. Like a tweet from January in which a stranger admitted to not knowing anything about Ms. Mescal’s brother, the actor Paul Mescal (best known for his breakout role in Hulu’s “Normal People”), but wrote that Nell was “hot” and “sings good.” “I want to kiss her on the mouth,” the person added.

“I was like, ‘So true,’” said Ms. Mescal, a 19-year-old Irish singer-songwriter. She became a microcelebrity online this year after her reaction to her brother’s Academy Award nomination went viral on Twitter. (Mr. Mescal is nominated for best actor for his performance in “Aftersun.”)

In a recent interview, Ms. Mescal discussed her music, her internet habits and the celebrity she’s hoping to bump into at the Oscars this weekend.

This interview has been edited and condensed.

Let’s start with your music. What would you play for someone right now who has never heard your work before?

I would play them my song “In My Head,” which isn’t out yet, but it’s going to be out soon. It’s an anti-love song about feeling like you’re always going back to someone that maybe you shouldn’t be going back to.

Earlier this year, you went viral on Twitter for your reaction to your brother’s Academy Award nomination. What was that day like for you?

It was the craziest day ever and also the scariest. It’s very surreal when you post something and then all of a sudden it’s like, “Oh, everyone is seeing this and also their parents are seeing it and their dog and the cat.”

“Scary” is a good way to put it. People often don’t think about that side of virality: It’s all fun and games until hundreds of thousands of people are paying attention to you.

I had, like, a thousand followers on Twitter and I had to be like: “OK, stop following me. This is the app where I totally talk about ‘Gilmore Girls’ and pretend I’m not a singer.”

There was a video of you and your brother singing together that floated around Twitter that day, too. The tweet read, “A reminder that Paul Mescal may not even be the most talented member of his own family.”

That was also the second time that video has gone viral. I was like, “That’s enough now.”

You seem to be an extremely online person. Do you feel like it becomes less fun to be online as more and more eyeballs are looking at you?

For a second there I felt quite safe, and I was like, “I’ve just, like, built this community of people that really care about what I’m doing and they care about the music and they care about the shows.” So then, when it’s like anyone and everyone is just all of a sudden watching you, you’re like, “Maybe I wouldn’t have tweeted so much about Roman Roy from ‘Succession.’”

What is the weirdest DM you’ve ever received?

I feel like I get some very weird Instagram DMs where people will just send me a photo of themselves with question marks. And I’m like, ‘I’m just as confused as you seem to be.”

You said you had about a thousand Twitter followers on Nomination Day. Now you have just over 15,000. It doesn’t seem unreasonable to say that a lot of people are getting to know you initially, at least online, through your relationship to your brother.

I think that if people find me through him, that’s incredible and wonderful. But I hope that they stay not only because they’re a fan of him, but because they like the music and not just because they want to see if I post, like, a photo of Paul’s elbow.

What’s next for you professionally?

I’m doing the festival circuit in the summer and “In My Head” is coming out on the 24th of March with a really cool video that I made with a lot of my friends. I’m playing with Birdy in London and in Dublin with her as well, which is a crazy full-circle moment for me.

Why is it full-circle?

Birdy is one of the main reasons I picked up a pen to start writing in the first place.

You’re also very active on TikTok. As a musician, do you feel pressured to use the app as a growth hack?

I’m trying not to go viral, which is maybe controversial. I feel like everyone’s looking for a viral moment. But I think the best way for longevity is just to build as naturally as possible. So if 10 people saw one video and 11 people see the next one, that’s a win.

How will you be spending Oscars Sunday?

I’m going to be with my family. I’m going to be with my brother Donnacha getting ready for some after parties. I can’t wait to be in the sun, though I did hear it was snowing in Los Angeles recently.

Who is dressing you?

Gucci. It’s really pretty.

Is there anyone you’re hoping to meet?

Everyone. Michelle Yeoh. If Michelle Yeoh walks past me I’m me passing out.