In that case, she would just need some sort of reason as to why she would be able to suddenly leave the Convent to go on a long and perilous journey up the mountain. Or at least to where Laharl is, since that's what I assume you want. Contrivances being what they are, maybe she's taking a break from tending to the sisters' horrific burns and wounds through one of the Convent's deambulatories and sees Laharl throwing some kind of showy tantrum from far away with his powers, due to his anger and helplessness at the stubborn Seekers?