I just noticed something rather peculiar.
Nikki's age is given as 19, which is fairly reasonable, although it doesn't give him much time to have established himself as a singer.
Marcy's age is given as 9, which I suppose isn't completely implausible (although she's really precocious)...except for one thing. If Marcy is 9, that means that Fargo and Zelbess were still together when Nikki was about the same age (even if we don't trust the Ultimania guide, which indicates Nikki last saw Fargo in 1011). However, when the party first boards the Invincible, Nikki does not recognize Fargo until he's told the name of the ship and has a chance to work backwards, although he should remember his father quite well (Nikki (Home) even remembers the furniture, for crying out loud...).
I can only think of three explanations for this, and I don't really like any of them:
1. Marcy's age is incorrect, and she should be at least 13-14, making Nikki around 5 the last time he saw his father. (This means that the Ultimania guide is also out to lunch.)
2. Fargo has really changed a lot since Nikki last saw him. This is the most plausible explanation on the face of it, but how different could a grown man really become in <10 years, barring severe and disfiguring injury?
3. Fargo and Nikki actually parted ways several years before Marcy was even conceived--but why?
Does anyone have any better ideas?