I've been using my "stylized A/pyramid with wings" logo as a brush so that I can put it on anything and not worry about the background, color, size, or anything. As a brush I can plop it down, put in any background I want, change the color or add layer styles...totally editable stylewise. So my point is that you should probably do something similar and that way it will never clash with the colors or paper of a map. If you want to emphasize more than just fantasy then make the M something techy or sci-fi. Or do away with the initials and include full text; put Fantastic in something gothic or scripty on top of Maps as something sans serif and techy.