I posted a theory about Leah's purpose in CC in this topic:
http://www.chronocompendium.com/Forums/index.php/topic,3519.0.htmlBasically, the logic of this is:
- the Planet removes Leah (and the whole of Gaea's Navel) from a different dimension
- as a result, Ayla isn't born in that dimension, and the Reptites easily defeat the humans
- that dimension becomes what we know as the "Dragonian dimension", and Dinopolis is built in its future
- the Planet removes Dinopolis from that dimension
- Serge's adventure occurs
- after the ending, the Planet could even bring Leah back into her dimension, thus nullifying the Reptite victory but sort of cleaning up the mess she created.