Harley is Harry's obnoxious cousin, but as for which cousin's parents is related to which one, it is never known.
Harley takes certain advantages of Harry in the following episodes, to name a few:
- In "Harry's Sweet Job," Harley talks Harry into hiring him for the job when his only co-worker, Margaret, calls in sick, but he only does it so he can have free samples (which are not allowed). While Harry is spending his lunch break doing trapeze practice with a partner, while serving a customer, Harley inconveniences a customer who asks for 4/8 hazelnut truffles (meaning four out of eight truffles being hazelnut), 3/8 mocha, and 1/8 caramel, by eating the latter two, leaving only the hazelnut ones. When Harry returns, receives the man's complaint, and replaces the missing ones, Harry asks him if he knew about it. Harley, with chocolate on his face, lies by saying he has no idea. As punishment, Harry responds, in chocolate letters, that Harley is fired.
- In the budget one, Harry plans a date only for himself and Jenna, but Harley talks him into taking him because of a bad day he is having, ruining Harry's budget, causing Harry to simply order a grilled cheese sandwich. As a result, to stick to the budget, Harry keeps talking Harley into not ordering any dessert so he can impress Jenna and stay on budget.