If your partner has any tendency to dream and fantasize rather than make solid, workable plans, you'll have an especially beneficial influence in their life, but even if they're a careful thinker and planner, you can still help to steady their mind and ground their thinking in practicality. In another lifetime, after all, you were their teacher; then you gave them just the sort of mental guidance that you can provide for them again in this life. They'll know you have a sharp mind and an eye for practicality, and will look up to you on an intellectual level.
When you give them advice, they'll take it seriously and will be open to learning from you. Through talking with you and making plans with your input, they'll learn to express themselves more clearly and effectively. This input of yours will be especially appreciated if they are shy or insecure about their intelligence, or how they present themselves to the world; even if yours turns out to be a short-term affair, you can have a positive effect on them in this way. They will model their self-expression after your advice in some way, which will help to further them both intellectually and also at a karmic, evolutionary level.