A person, generally male, who tries to turn a friendly platonic relationship into a romantic one by ensuring they are available at beck and call and performing numerous helpful favours over a long period of time such that they gradually compromise his or her's own dignity in doing so.
Andy: Do you think that dude Eddie likes Callie? They're friends, but he sure keeps going out of his way for her. I wonder if she notices.
Fabricio: He's such a legionnaire.