The German/Vietnamese child of Gustav and Lau Brandt, the girl who would become Mantis was given up to the alien Priests of Pama, a sect of the Kree who believed in the "Celestial Madonna", a legendary being who would give birth to the Celestial Messiah, deemed to be "the most important being in the universe." Excelling in her martial arts studies with the Priests, gaining a heightened control over her physiology in the process, Mantis has her memories erased when she becomes an adult and sent back to earth in order to gain life experience. Becoming a barmaid/prostitute in a Vietnamese bar, she meets the Swordsman, Jacques Duquesne, and accompanies him back to the United States after helping him regain his self-respect. Joining the Avengers alongside him, Mantis soon became involved in many of the team's adventures, motivated partially by her growing sexual interest in the Vision. As it was, Mantis was unaware of the Swordsman's love for her, and only realized (and reciprocated) it during his deathbed confession after being mortally wounded by Kang the Conquerer in his own quest for the Madonna. Shortly thereafter, Mantis discovers that she is, as was suspected, the Celestial Madonna, and leaves Earth with the planet's eldest Cotati in order to give birth to the Celestial Messiah.
Bearing the child, whom she names "Sequoia", Mantis (now calling herself "Mandy Celestine") is compelled to give up the child to the Priests of Pama, joining the Silver Surfer in his adventures shortly thereafter, and even beginning a relationship with the former herald of Galactus. Growing increasingly dissatisfied with her life, particularly after her powers began to alter, Mantis is caught in a massive explosion and presumed dead by the Surfer. In fact, Mantis survives the blast, but the stresses placed upon her in recent years literally cause her to fragment into multiple versions of herself, each bearing a different aspect of her personality and fragmentary portions of her memories. One such portion becomes a member of the West Coast Avengers for a time, before leaving the team to raise her son.
Eventually, Mantis manages to recover and merge all the fragments of her personality, leaving her whole once more in time to help the Avengers stop Thanos from killing her son. During this period, she resumes her pursuit of the Vision but eventually ceases upon realizing that the connection between the Vision and the Scarlet Witch is genuine and strong, despite their estrangement.
