You'll have to forgive Jessie J if she has to sit down once or twice during her VMA performance as house artist: she's been nursing a broken foot after sustaining an injury in June. But after watching her absolutely annihilate her VMA rehearsal today (if there were a VMA for Best Voice, I'd lobby for Jessie J to win like six of them), it's apparent that she'll have asses out of seats, even if she's sitting in hers.

But if you're like me, and Jessie J had you at "Do It Like A Dude" when you first heard it last year or when her Who You Are album finally came out, you already knew that not only can she write a perfect party jam (perhaps you've heard of a little under-the-radar B-side called "Party In The U.S.A."), but she's a born belter. And as any die-hard Jessie J fan -- also known as Heartbeats -- can attest, Jessie J isn't just about subverting sex roles with a sneer and an unsubtle crotch grab. She's got a sweet side too, as evidenced by her shimmering new single, "Domino," which she'll perform at the VMAs on Sunday in a move that's about to take her from "who's that girl?" status to it-girl status.

"People have heard 'Domino' and said 'it's nothing like you.' But I'm like well the album's really eclectic anyway, and I never go into the studio and say 'I wanna do another song that's like "Price Tag" or another song like "Do It Like A Dude",' she said. "I listened to a lot of Whitney and Prince... and we kinda just wanted to write a song that's timeless, that's fun and uplifting."

+ Watch Jessie J discuss "Domino," her Heartbeat fan base and more after the jump.

And speaking of uplifting, watching Jessie J nearly get choked up when I asked her about her Heartbeats was almost as endearing as what she had to say about her die-hard fanbase and the built-in support system they share: "They're amazing, and they're the only reason I'm here at the VMAs and people know who I am," she told me. "They support me and buy my albums and singles, and they stand outside hotels, and they come to shows, and they get tattoos of my lyrics and they cut their hair like me. You have to love your fans. That's why I call them my Heartbeats, because without them i wouldn't be here."

And if you needed another reason to adore Jessie J, well then here it is. Next year she'll be shaving her head to raise what she hopes is $1 million for charity. And she wants to do it with her fans of course.

Watch Jessie J discuss "Domino" and her Heartbeats, and watch her reveal why she's going bald for a good cause. And whatever you do, don't miss it when she performs live all throughout the VMAs this Sunday night.

Watch VMA House Artist Jessie J perform live at the 2011 MTV VMAs live from Nokia Theatre L.A. in Los Angeles on Sunday, Aug. 28, at 9 p.m. ET/PT on MTV and MTV.com. Catch the live preshow at 8 p.m. ET/PT and cast your votes for Best New Artist up until the show airs!