There’s a striking difference in Aspen Ison’s demeanor when she walks the halls at Peninsula High School and when she stands in the pitching circle.

In social settings, she’s friendly, easy-going and a bit shy around strangers. But when she toes the rubber and gets ready to wind up, her smile disappears and her eyes lose any trace of compassion.

During the past three seasons, opposing batters have learned how unfriendly Ison can be. A back injury slowed her down at the start of her freshman season, but once she got healthy, she led a huge surge that nearly catapulted the Seahawks into the Class 3A state fastpitch tournament.

Ison pitched nearly every inning for Peninsula in the 2011 and 2012 seasons, both of which ended successfully. Two years ago, the Hawks won the West Central/Southwest bi-district tournament, and last year, they captured the program’s first South Puget Sound League crown.

Her last two seasons have been phenomenal as the Seahawks have gone 40-12 and reached state twice. As a junior, Ison started 25 of 26 games, completed 24 of them and threw six shutouts. Her ERA was 1.35, and she struck out 240 hitters in 171 innings.

The scary part, coach Melissa Miller said, is she could be better as a senior.

“She’s toned up a lot and gained a lot of strength physically,” said Miller, the Seahawks’ fourth-year head coach. “As far as her pitching goes, she’s pretty darned tough mentally.

“I think it’s nice to see her smiling a lot more. I think she’s always been intense, and she hasn’t lost that intensity, but she’s able to smile a little bit.”

Ison became a softball player on a whim. As she grew up, she was a dancer, but she eventually grew weary of it.

Her dad, Mike, suggested softball, and Ison said she immediately fell in love with it. She attended open gym sessions with Miller during her middle-school years, so the transition to high-school ball wasn’t a big deal.

“She’s always been like, ‘When are you going to be a freshman? When are you coming here?’ ” Ison said of her coach. “So I always expected to come in and do well.”

Ison’s craft has largely been shaped by playing with a couple of South Sound select teams. For the past two years, she’s worked with the Washington Acers.

“Those girls play year-round,” Ison said, “so it’s just amazing to be surrounded in that atmosphere, and to have so many opportunities to go out of state, meet so many new people and see dedicated softballers, how amazing they are.”

It was through select softball that Ison began to form relationships with college coaches. The recruiting process began well before her junior season, when the NCAA allows direct contact between coaches and high-school athletes.

“You can call them, but they can’t call you back ... so you really have to press them and get your name out there,” Ison said. “It’s really up to you.”

Ison attended a camp at the University of Washington, and that’s where she was first acquainted with Western Washington coach Amy Suiter.

The Vikings have consistently kept tabs on Ison, including a visit to Peninsula’s sub-district tournament games last May, and she signed with the NCAA Division II school in November.

Ison likes the fit with Suiter and Vikings assistant coach Albert Rivera, and indications are she could play right away.

“On my first visit up there, I asked what she needs, what she’s looking for,” Ison said, “and I really think that’s the place for me. I can go in and play, and that’s what I want to do.”

Ison is equally driven academically, and she plans to enter Western’s pre-medicine program for a potential career as a doctor or dentist.

While Ison’s right arm is the first thing recruiters usually notice, she swings the bat well, too. She finished 2012 with a .349 average, 19 runs scored and 20 RBIs.

As a pitcher, Ison often can decipher what the opposing hurler might do in specific situations. And she’s looking forward to hitting in college.

“It gets you from a pitching mindset, and you take a break,” she said. “I’ll be like, ‘I have to hit. I need to focus on something else.’ So if you have a bad inning, that’s a really good way to get your mind off of it.”

The Seahawks lost two of their leaders last spring as Texas Tech-bound shortstop Anne Binschus and third baseman Kayla Stelle graduated. But Ison’s departure following this season may be even more difficult, Miller said.

“It’s going to be a huge loss when she leaves,” Miller said. “She’s irreplaceable in my eyes.”

However, the Seahawks have a large group of potential pitchers for the future, and Miller thinks Ison could exert an influence on them.

“I’m hoping before she leaves she can work with our younger pitchers and give us something to look forward to next year,” Miller said. “I think people are expecting us to die when Aspen leaves.”