'Shadow of His Thoughts' by J. Michael Straczynski

Six days after his coronation, Emperor Londo Mollari struggles come to terms with his new Drakh Keeper, and continues to be plagued by terrible dreams. As the work to rebuild his people’s shattered world progresses, Londo learns that he is bound by tradition to journey to the river Tuwain, where he must oversee the inauguration of a new prophetess supreme…

Notes:
*Set in late 2262, a few days after Londo's coronation

*Published in 'Amazing Stories' #597