Roland is an ISTP for sure. He doesn't talk much until it's necessary, often relies either on his gut feelings or "ka". Obvious Se/Ni user. Also he is a TiFe user because he tends to let others making their own choices instead of controlling them.
Eddie is also a textbook ENTP with no doubt. Unlike Roland, he likes to make facetious commentantaries based on resemblances. By reading the books you'll be able to notice that he's very aware of possibilities and notices coincidences(Ne/Si). Also he tends to theorize and hates, when his questions that interest him someone doesn't answer (Ti). His Fe is expressed by caring about people he sympathizes like Susannah.
I guess Susannah is an ISFJ. Tends to remember about her past and therefore she loves to talk about it. Also she's quite down-to-earth. I saw a Tumblr post telling Susannah is ISTJ but I think she's a Fe/Ti user. She shows empathy to others like when Callahan told his story. And she doesn't seem to control others like ISTJ usually do. Odetta and Detta are quite hard to type. Odetta is very similar to Susannah but she seems to be less confident. I guess she's ISFJ too but less developed. Detta is obvious extraverted, seems to be a perceiver and a Ti user(although she might be also a Fi user due to her selfishness). I guess ExTP fits her best. I'm not sure if she's a Se or a Ne user. She seems to be really focused on the present and just wants to run away from Roland and Eddie, but while planning out the attack on Eddie she seemed to use Ne(or was it Ni? Was too good for an inferior function).
Jake was quite hard to type. I was stuck between INFP and INFJ. I thought he was INFP because he tends to make his decisions based on what's right and what's wrong. Also he tends to think like a Ne user(because Stephen King is a Ne user). But then I found out that he desires to find out where he belongs to. Also he takes signs very seriously. Looks more Ni to me than Fi(they are hard to distinguish). Jake seems to consider the world as the whole. Not like a Ne user, who tries to connect puzzle pieces but like a Ni user who has already connected all the pieces and views the whole picture. I think that a student's success may not be dependent on their financial situation. I frequently struggle with the learning process myself. in particular with challenging assignments. And the
essay writing nursing has been really helpful to me. Additionally, I must prepare qualitatively, but I am unable to do it on my own. Rarely, you can also notice him rely on his instincts like Roland. The only difference between Roland and Jake is how down-to-earth they are. While Roland is very down-to-earth, Jake oftens thinks beyond the present.