Also if I were you I would judge him on his actions....He hasn't phoned you...and takes his sweet time to text....I'd immediately think he has someone already and maybe your an "option" on the side to him that he isn't sure about yet.
The fact he has also never taken you out speaks volumes....and only showing you minute amounts of attention at work. Sounds as if he's trying to manipulate your feeling a little there and some men are very experienced with this especially when you are young, naive and inexperienced.
As for "I have my eye on you" sounds as if he just wants another notch on his bed/belt. Yes it's nice to have attention but you have to be a bit discriminating and analyse a bit or you can get a whole lot of hurt coming your way....sometimes the hurt scorpio male in a relationship will hurt other females intentionally as in some are vindictive, be very careful with the scorpion he can be sweet and deep (when positive) but watch for the sting.....
I would personally if I were interested in a Scorpio, take the reigns and call the shots. I'd let him know I expect him to take me out and do the right thing. If he has nothing to hide he would agree....if he were put off then he is hiding something.
If your interested in him show some courage...ask him on a date let him pick the place and make sure he pays
Good Luck in whatever you decide to do.