Basil Hallward is the poor but brilliant artist that paints Dorian Gray's perfect portrait--so he's slightly guilty and he relates to Justice. My first draft of the deck had Basil as the Queen of Cups, because he lacks the emotional control that the King usually brings to bear. When Basil appears, you need to be considering your own creative spark--where does your interpretation come from?--or your own sexual desire--am I attracted to people who are bad for me?--or your emotional well-being--are you happy in your life?--or your aesthetics--is my life as beautiful as it ought to be? As the King of Cups, Basil wants you to either give yourself over to pure love OR is terrified that you gave yourself up for love. He represents the end of the emotional journey that you're taking.
Reversed: Basil has no real backbone; he's happy to give up himself to make others happy, even when those people don't appreciate the effort, or pay his kindness with cruelty. Examine your life for unequal energy between you and others.
Basil shares a novel with Dorian Gray, Judgement, with whom he has a loving but tragic relationship, and Lord Henry, Knight of Swords, with whom he has an antagonistic relations (or, possibly, unresolved sexual tension).