In the canon:-=== Jocasta appears as a senior student at the Assassins' Guild School, who is sent on an ultimately humiliating assignment by her teacher Alice Band to get up close and personal to Sam Vimes.
She ends up in the dunnikin at Ramkin Manor reflecting on her over-confidence, which is what Alice meant to happen all along.
In the Pessimal Discworld:-Edit
Jocasta is next seen several years on, as a newly graduated licenced Assassin. In the opinion of Pessimal, Australian actress Miranda Otto (Eowyn in "The Lord of the Rings") captures the personality beautifully. In keeping with her canonical appearance, if there is a large amount of crap to be deposited, it generally lands on Jocasta. To the point where her nickname is "Mucky Pup".
She appears in:-Edit
as principal character
as a cameo