Cyteen III
From back cover Warner paperback April 1989:

ARIANE EMORY HAS RETURNED.
BEWARE.
WHAT IS ARIANE?

Fifteen-year-old Ari Emory must grab and wield vast political power.  She must prove her existence and identity to a world that fears her, that thinks her a programmed living puppet -- because Ariane Emory is the replicate of the dead tyrant whose name and genes she bears.

Her struggle will rip the social order of planet Cyteen and turn family into foes and enemies into allies, as the possibility of eternal resurrection fuels the lusts of rulers and the terror of the ruled.

Ari alone knows that her predecessor discovered a "Worm" -- a flaw -- in the basic fabric of civilization.  If not corrected, it will inevitably destroy humanity.  And only Ari Emory can hope to stop the Worm, if given centuries of life and unlimited power.

But someone murdered Ariane Emory once.  And stands waiting to kill her again...
Ariane Emory (Fictitious character), Fiction, Cyteen (Imaginary place), Fiction, science fiction, general, Cyteen (imaginary place), fiction
C. J. Cherryh
Carolyn Janice Cherry (born September 1, 1942), better known by the pen name C. J. Cherryh, is an American writer of speculative fiction.