A longtime associate of the Avengers, the elemental Crystal was familiar with the team through her temporary membership in the Fantastic Four and her subsequent marriage to longtime Avengers member Quicksilver, as well as her place in the Royal Family of the Inhumans, a reclusive race with whom the Avengers have been allied on several occasions.

     In later years, tensions in Crystal's marriage (exacerbated by the mental manipulations of Maximus the Mad) led Crystal to desert her husband and their daughter, Luna, for an affair with a real estate salesman named Norm Webster. She subsequently tried to renew her romantic relationship with Johnny Storm, the Fantastic Four's Human Torch, who was married himself by that time. 

  
     She eventually returned to Quicksilver and Luna at the urging of the Inhuman Royal Family, but the wounded Quicksilver stayed aloof from his prodigal wife, and eventually left the Inhumans to resume his former life as an adventurer, first with the western Avengers and later with X-Factor.

     Crystal herself, lonely and feeling guilty about her past misconduct, offered her services to the Avengers after assisting them against the alien Brethren, hoping to find a new sense of purpose and atone for her mistakes. She soon became an integral member of the Avengers and served a lengthy term of duty, though her membership was complicated by her abortive romance with teammate Dane Whitman (Black Knight) and Quicksilver's subsequent return to the Avengers and attempts at reconciliation. 

     Sadly, just as Crystal and Quicksilver had begun to rebuild their marriage, Crystal was among the Avengers lost and presumed dead during the team's battle with Onslaught. 

     She later returned from that seeming demise alongside the other lost Avengers and was happily reunited with Quicksilver and Luna, but the family soon splintered again. Quicksilver and the Black Knight engaged in a physical battle for Crystal's affections, and she was so disgusted by this display that she renounced them both, separating from Quicksilver again. 

     Crystal has devoted herself to Luna and the affairs of the Inhumans of late, though she has assisted the Avengers on occasion. When Quicksilver became suicidally depressed after losing his powers, Crystal and the Inhumans took him in, but he betrayed them by stealing the Inhumans' mutagenic Terrigen Mist, using it to give himself new powers and to give his previously-human daughter Luna powers as well.