I just blogged on moon in Capricorn today so I’ll take a shot at this one.
Leo is very loving and wants to show love. This Leo appears to have grown up in an environment where the love was not consistent (moon, Uranus, Neptune and Saturn in Capricorn opposite Jupiter and Venus in Cancer). I’m guessing he’s worried that if he shows all that Leo love,the rug will be pulled out from under.
Sometimes I see this with someone abandoned or adopted. In adoption, The family may be loving, but the individual still never feels part of the unit. In abandonment, there can be an obsessive need to track other’s movements so that they have not disappeared. Something along those lines seems to have occurred. It feels strongly unpleasant.
This 3rd house sun Leo with Mercury in the 4th might gain the sense of being loved by being in a teacher role. Moon in Capricorn wants respect and Leo wants hero-like admiration. The 3rd house is communication and Mercury in the 4th suggests that communication needs are strong.
Mars in Taurus and sun in Leo are both fixed, strong and proud. You can suggest things to this person, but he will have a crazy set of “honor code” type rules in his mind – an honor code no one in his life has followed.
So, yes, I believe this person is capable of love but has a lot of inner fears to work through.
Here’s the blog on moon in Capricorn http://ohioastrology.wordpress.com/2012/04/28/moon-in-capricorn-and-remains-of-the-day/