i'm going to try to describe him. i've heard ESTp/ISFp as possible types. he even has some INTp qualities, i think. i can't really figure him out at all. i'm fairly sure his wife is an INFp or an ISFp.
he's generally very jovial, kind of private, but also not private at all. like at parties and what not, he's very funny/has a good sense of humor. if someone "crosses the line" with him in conversation or acts aggressive/loud/argumentative, he gets very quiet. he's really very docile in a way, but also very manipulative/not that concerned with what is decent (e.g. not leeching tons of money out of your mom when you're married and have taken on the responsibility of a wife, which is my dad's major beef with him.) does not forgive easily. can be incredibly childish in these matters and i think he takes my dad far too seriously sometimes (my dad can seem overly-dramatic.)
doesn't keep jobs at all, although i am convinced he's really smart/qualified/could do whatever he wanted to do if he'd apply himself or if his wife would give him some freedom/or if she'd work or something while he goes to school/if they wouldn't spend tons of money on useless stuff. it's a weird cycle that i actually think is plenty stoppable, but they don't seem to care/are content, i think, w/ their lot in life.
can talk my mother into buying damned near anything she doesn't need. he'll usually only do this when there's something in it for him, or if it's some electronic item he thinks he needs. he can convince her into getting it, whatever it is. spends like crazy, then asks my mom for money, which in turn makes my dad mad because he thinks my brother needs to grow up. they are up to their ears in debt. eats anything, and lots of it, mostly crappy stuff that is completely devoid of nutritional value (like a lot of fast food.) can talk about books/movies/lord of the rings type stuff and i think this is pretty much all that interests him anymore, although he used to be more diverse. loves horror movies. pays absolutely zero attention to his appearance. lives for the holidays and parties. loves his two dogs. weak self-control.
oh, and if i ask him to do something like sell some item for me for me on ebay (i bought this PDA that i wound up never using, which is something i should have sold myself,) he'll just take it for his own and say that he'll pay me back, but of course he doesn't. i have to go physically remove it from his house/ask for it verbally. he can slowly claim a lot of your belongings as his if you leave them there.
they (my brother and his wife) have this weird mutually parasitic relationship. like she ties him down a lot, spends a lot, and then tells him to go get money from my mom. he comes up with some great reason why he needs this money and she hands it over.
i think in highschool he was generally thought to be one of the kids with no conduct problems or anything like that. like he was sporty/good kid/but probably not stereotypically "manly" enough.
humor-wise: he likes stuff like flight of the conchords.
i don't know what we are relations-wise.