Every time Bonnie Raitt performs in the Twin Cities, her older brother, Steve, a local music producer, sits in on one song. On Thursday at the State Fair grandstand, Steve, who died in April of brain cancer, informed nearly every song in a remarkably emotional and unforgettable evening.

His little sister's slide guitar was darker and moodier, her emotional ballads were more deeply felt (with Raitt on the verge of tears a couple of times), and her excessive chatter was filled with sadness, celebration and many things Minnesotan, from shout-outs to Steve's friends to a mention of the previous night's walleye dinner to an expression of her love for the Minnesota State Fair.

After Taj Mahal's opening exploration of various shades of the blues, Raitt, 59, took the stage and dedicated the show to her brother, saying, "As far as I'm concerned he's standing right here with me."

Under these extremely personal circumstances, she relied often on Twin Cities keyboardist Ricky Peterson, who joined her band this year and was one of Steve's best friends, to lift her up musically and spiritually. She sat next to him at the keyboards singing the lump-in-her-throat "Nick of Time," which caused her to well up and, in the end, literally lean on Peterson and then kiss him on the lips.

After her stinging slide solo to end "Love Sneakin' Up on You," the song Steve used to always sing with Bonnie, she closed her eyes and blew a kiss to the sky. Then she reached new emotional heights with her always penetrating hit ballad "I Can't Make You Love Me"; afterward, she slunk across the stage and gave Peterson, who had ended the piece with a soulfully jazzy solo, a long, long kiss.

At that point, Raitt summoned out Mahal and his Phantom Blues Band for a two-band jam. "The gloves are coming off," she declared, "and all the sadness put aside."

Raitt relished playing with a horn section for a change, and she clearly dug duetting with Mahal, a friend of 40 years but a first-time tour mate. They got playful on the sassy medley of "Tramp" and "Scratch My Back," and tore it up on her snarling "Gnawin on It" (dedicated to Peterson and his wife, Lu) and the rockin' "Comin' Home."

Raitt has been highly emotional at the State Fair before -- in 1990 on the night after her friend, guitar hero Stevie Ray Vaughan, died in a helicopter crash, and in 1998 when her mom sang with her for the first time in public (which Raitt mentioned on Thursday).

But, on this 100th anniversary of the grandstand in front of 7,275 people, Raitt showed how her blues/rock/pop/R&B music, filled with pain and joy, was the perfect way to grieve and celebrate her love of her brother and best friend.

For a set list, go to www.startribune.com/poplife.

Jon Bream • 612-673-1719