Não é certo se Guinan e Q travaram uma guerra juntos, tudo o que sabemos é que eles se conheciam de antes.
Wiki alpha de memória de Star Trek:
Guinan had "some dealings" with Q sometime during the 22nd century and indeed other members of the Q Continuum, some of whom she said "were almost respectable". Her exact relationship with Q remains unclear, though it was evidently hostile. Q described Guinan as an "imp" and stated: "where she goes, trouble always follows".
Também é importante adicionar o seguinte.
Wiki alpha de memória de Star Trek:
She was an El-Aurian, a race of "listeners" who were scattered by the Borg. Q, however, once suggested that there is far more to her than could be imagined.
Mais uma explicação poderia ser que os sobreviventes remanescentes do encontro borg estão perambulando pela galáxia em alguma missão, o que explicaria sua aparição na Terra todos esses anos atrás.
Her species is long-lived, and she is somewhere between 500 and 700 years old when she joins the Enterprise-D. "Time's Arrow, Part I" reveals that she visited Earth in 1891, and "Rascals" establishes that her father was 700 years old during that episode.