At first Leo Wyatt just popped up in the beginning of the series as a (really) cute handyman, who was immediately smitten with Piper, and vice versa. The sisters soon learned that he was much more ~ Leo is a "whitelighter", their intermediary with The Powers That Be, a virtual encyclopedia of the supernatural beings and events they encounter, and has the power to heal. When he "travels" in a srpinkle of light, it's called orbing, and he can take others with him, which he has done several times. He is assigned to the Charmed Ones as a guardian and protector. Leo was actually a young doctor during World War II, and was an exceptionally good person, so when he died, TPTB gave him immortality as well as his healing and orbing powers. While Leo and Piper did fall in love, there were many obstacles to overcome before they did finally marry, in the middle of the third season, in the company of a small group of family and friends