We really weren't that surprised when Ana Lucia put a bullet into Shannon's heart on "Lost" earlier this month.

"You know it was inevitable," laughed Michelle Rodriguez, who plays Ana Lucia.

Since her breakout role in 2000's film "Girlfight," Rodriguez has built a career playing tough chicks, each one more relentless than the last.

On "Lost," she has emerged as the island badass.

"It's either that or be some vulnerable chick in a relationship," she said, "or rip your clothes off."

Ripping someone's face off is more like it.

Sawyer — with whom Ana Lucia has an immediate if slightly spiteful sexual chemistry — called her "Rambina" (one of the kinder names he used for her).

Then he threatened to kill her. But that was after she socked him in the jaw and tossed him in a ditch.

But it's all foreplay.

"You never know with two people who are complete opposites — one responsible, one a complete joker," said Rodriguez. "It's hot when two polar opposites get together. I think it's more interesting that way."

Producers Carlton Cuse and Damon Lindelof are indeed cooking up a love "quadrangle" between Ana Lucia, Sawyer, Kate and Jack.

Last week, we saw Kate hovering tenderly over a still ailing Sawyer.

"Our goal was to have more romance in the show this season," said Cuse. "We're very much going to explore the relationship between the four of them."

The Nov. 16 episode, "The Other 48 Days," revealed the harrowing days endured by the other castaways. And Ana Lucia's steely exterior showed signs of strain.

"You see some of that," she said. "I'm an open book. It's hard for me to keep things inside."

The puppet masters confirm they're not done pulling Ana Lucia's strings.

"Exactly what is going on with her character will be one of the big surprises this season," said Cuse.

They won't answer any specific questions about the mysterious "others" on the island or the bizarre whispering presence, but Rodriguez has her own theory, grounded not in black magic but in technology.

Because they're kidnapping children, she said, "I can only assume that the others are a genetically enhanced race who can't procreate, and that's why they're stealing kids. And I'm thinking that the reason why all these crazy whispers are going on is they have some sort of machine, kind of like the Wizard of Oz's, where it's this guy behind this gadget."

Her hypothesis is pure conjecture. But the tenacity she brings to her characters is very real.

Rodriguez, 27, had little acting experience when she attended an open casting call for "Girlfight." She beat out more than 300 actresses also vying to play a female boxer. She spent hours perfecting her right cross at a gym in Brooklyn. But she learned tenaciousness long before that.