In Act 2, Scene 3 of The Merchant of Venice, Jessica bids Lancelot Gabo goodbye as he prepares to leave her father, Shylock's, service. She opens up to him and tells him he has been a source of fun in their all-too-serious house, and sends Lancelot to Bassanio's dinner with a letter for Lorenzo. Lancelot predicts she will marry a Christian, and they both cry at parting. Once Lancelot is gone, Jessica hopes Lorenzo will get her message and come to take her away and marry her.
Lancelot is a silly character whose primary purpose is to serve as comic relief in the play, but Jessica's judgment of her father is more reliable. She describes her house as hell and credits Lancelot with bringing a bit of merriment into it. If the only other person who lives in her house is Shylock, he's clearly the source of her unhappiness. Unlike the Christian characters in the play, Jessica has no prejudice against her father, quite the opposite. She should be predisposed to love her father, so whatever she feels for him is based entirely on his actions toward her throughout her life, and those actions must not have been good.
Her desire to escape from her father's house is the clearest evidence. against Shylock's character presented thus far in the play, as his negative qualities have until now been Jewish stereotype-based.