TO BE AXL, ROSE, LEAD SINGER AND chief hothead of Guns N' Roses, is to be misunderstood. Just because he occasionally shows up late to his own concerts or launches into lengthy onstage tantrums doesn't mean he's a callous person. In fact, it turns out that rock's premier nasty boy has feelings—as well as anatomy—that can be bruised.

Consider the legal action that Rose, 31, brought Aug. 27 in Los Angeles Superior Court against Stephanie Seymour, 24, the Victoria's Secret supermodel he had reportedly been engaged to marry. The two broke up in February, and Rose is now suing her for assault, battery and the recovery of more than $100,000 worth of jewelry, including a diamond, gold and turquoise necklace and a 4.5-carat diamond engagement ring. "He wants them returned," says his sister Amy Bailey, 28, who runs the band's fan club. "Rather than keep them as a sad and sorry reminder, he wants to give them to a child-abuse charity."

Seymour, who once dated Warren Beatty and is now linked with Peter Brandt, 45, the polo-playing owner of Interview magazine, met Axl in 1991, when she was the star of GNR's "Don't Cry" video. At first, all was bliss. "The whole relationship was wonderful," says Axl's sister. "Until last Christmas."

That's when Stephanie organized a yuletide party for Axl and several dozen friends and relatives at his Malibu home. According to Bailey, the two had been bickering and Axl, preferring to be alone, asked the guests to leave around midnight. Seymour was in a more festive mood. After she reportedly called him a name, a 45-minute brawl ensued during which Seymour allegedly swung a chair at Axl, just grazing the singer, then connected with a fist to the groin. "I never saw Axl strike, punch or slap her," Bailey says of her brother, who is renowned for his explosive temper. "[Stephanie] wants to push things to the edge."

Seymour denies all, not just the assault. "I strongly disagree with Mr. Rose's version of these matters," she says through a spokesman. "I was never engaged to Mr. Rose." She intends to donate the jewelry in question to charity. As for Axl, she says, "I have gone on with my life, and I hope that he can do so as well."