MP has always been a control-freak - he's said as much himself. I believe JP really likes to be in control of the situation as well, tho it's not as obvious as MP. JR has probably been the most experimental of all the members of the band, especially with his incorporating of new instruments and/or software for coming up with new sounds and the like. JM has always been the quiet member of the band. MM is the mathematician of the band (or so it seems) and is extremely humble and outgoing. Hard to describe JL as easily, altho he's always been a very pleasant person to be around.
For the record, MP and JL were not always at odds with one another. When JL first joined DT, he and MP were particularly close. But over time, their relationship became strained on at least 2 occasions.
In general, I've met all of the guys in the band (including Derek Sherinian and Charlie Dominici) and every single one of the guys have been friendly to fans and humble about their accomplishments. None of them ever came off as a rockstar that was too good for you. Even when I met Kevin Moore (in January of 1993, along with the rest of the band), he was pleasant and liked to joke around; not sure what he's like these days.