This person will have a strangely magnetic hold over you, and as long as you're both open and honest about your what you want out of this friendship, this influence should make for a positive experience for both of you. Be aware, though, that this friendship will probably take on an all-or-nothing quality. Any lack of interest on your part, especially, will lead to your pal getting possessive, jealous and generally hard to deal with.
So if you're not really into this friendship you should be upfront about that fact and let it go. Likewise, if you would like to maintain a strong friendship, let them know that as well. As long as you treat each other with the honesty and respect that you both deserve, you'll develop an strong kinship that will provide a good support system for both of you.