Fire and Water… the compatibility of the two of you is something to be questioned. Fire often dries Water up, and if this doesn’t happen Water will tend to flood over Fire, putting out your flames.
Pisces has a special capacity for self-sacrifice, and will do much in order to stay in a relationship with you if he feels actual love for you. Pisces is also subordinate by nature, and you will always find yourself in the lead position in this relationship, which will be just fine by you.
You may be attracted to your Pisces’ mysteriousness and compassion, her need to help everyone around her and her ability to do so. However, there are a lot of ways you two are different… Pisces wants to stay home, and would rather dream – exploring mental avenues instead of physical ones, like you prefer. Pisces is sentimental and emotional, something you don’t know much about. She lives by intuition and you prefer to lead by logic, which may bring some problems between the two of you.
However, as I’ve said, your Pisces is always willing to sacrifice his own values for the good of his partner, so you may yet convince him to get off the couch and come on an adventure with you… and he might even enjoy himself!
Your sex life will be novel at first, having a partner who has a willingness to do most anything for you. This may get boring after awhile though; why can’t she think for herself, do something new and interesting for a change?
This relationship may not be what you are looking for after a few months. Pisces is just too inactive, not action-oriented enough for a typical Sagittarius’s liking. Of course, if you two are truly in love, anything is possible… so you may want to give it a chance!