Joel: INFP (probably... not totally sure on N, but he's not an ISFP).
Clem: ESFP, just totally, like, jah (an ENFP has much more obvious big-picture clarity, Clem is really usually caught up in the dizzying cycle of sensory stimulation and is very very impulsive)
You know how one INTP combo can be Ti+Si style? Imagine an Fi+Si (withdrawn -- and Joel is extremely withdrawn) style now. I'm thinking it would look a lot like Joel... very timid, fearful, strong inner judgments. He also could easily accept Clem's external quirks even tho she was socially a disaster; I don't see ISFJ doing that whatsoever. This is because Joel's Fi valueset allowed for expression of individuality. But she also threatened their safe haven and prevented him from risk-managing his life, and he felt used and violated by her aggressive emotional outbursts.