jo is an extrovert who keeps random hours thanks to her work, so we can say they met while he was covering a very late shift and she was in desperate need of coffee? she's the kind of person that's happy to pursue someone and then will disappear for weeks before hitting them with a "u up?" text like she didn't just not contact them for 28 working days. and depending on what you'd prefer they can have an on/off love/hate where both of them get frustrated with the other and argue, don't talk, jo creeps back, ad infinitum