Chapter 4 of Star Wars: Heir to the Empire (1991) (EU: 9 ABY) by Timothy Zahn.
Five years after the Empire’s defeat over Endor in RotJ on the ex-Imperial capital of Coruscant, Luke, Leia, and Han are struggling not only with their evolving identities, but also with the demands on their expertise as the militaristic Rebellion aspires to establish a legitimate and functioning government.
Meanwhile, led by Warlord Grand Admiral Thrawn, the Empire is gathering strength to regain lost ground against the New Republic. His plan takes an expedition to Myrkr, where Captain Pallaeon and Tallon Karrde parley for the Empire to collect the native ysalamiri. Karrde suspects it is a tool to use against Luke Skywalker, though to what end he can only guess.
Grand Admiral Thrawn and Captain Pallaeon travel to Wayland, a low-tech world hiding a storehouse of the late Emperor's personal treasures and technology salient to Thrawn’s grand plan. Expecting a Dark Jedi Guardian, Thrawn thwarts the usurping ruler Joruus C’baoth’s snare with a demonstration of the ysalamiri's unusual ability to vacate the Force.
Thrawn bargains with C’baoth to secure his allegiance in exchange for the capture of Leia’s unborn Jedi twins, whom C’baoth would mould as he sees fit. Pallaeon believes C'baoth to be unstable and a dubious ally, despite Thrawn’s confidence. Thrawn reveals that C'baoth is a clone of a Jedi Master, whose assassination Thrawn was personally involved in before the Clone Wars and Great Jedi Purge.