A couple of years back, if someone had told Shawn Sears — a former rock band drummer — that he’d be a registered member of the Taylor Swift fan club, he wouldn’t have believed it.
That was before Sears’s tween-aged daughter fell in love with the pop queen of breakups. Before Sears learned that the best way to score tickets to Swift’s Red Tour — which has touched down at Gillette Stadium for sold-out shows Friday and Saturday — was to get on Swift’s mailing list. And before Sears himself, a 40-year-old Web developer from Lynn, started turning up the radio when his favorite Swift song played. “It’s ‘I Knew You Were Trouble,’ ” he said, without shame.