Really, it is EXTREMELY difficult* to base much of anything on a few lines of lore. One of my characters is going to go down the path of Dark Knight due to a unusual situation he has been put into, but it may be more using the concept than actually joining the 'order' of dark knights. It all depends really on the extent of the Dark Knights lore limitation.
However, if we consider them sort of being the Ishgardian version of the Rogues guild. There is a lot of flexibility as to what can motivate or drive them. I don't think that Jacke would abandon his code of ethics even if he got magicaly moved to Ul'dah. He would just have waaaaay to much work to keep up with really. Likely, the infamous 'the elementals don't want her to be healed' conjurers in Gridania would have a visit from the rogue.
Until we get more lore on them it really is impossible* to say if a character is going to follow the lore or not, unless they are preplanned to be a DRK that follows the blurb as the character concept.
*Well.. in my opinion.
However, if we consider them sort of being the Ishgardian version of the Rogues guild. There is a lot of flexibility as to what can motivate or drive them. I don't think that Jacke would abandon his code of ethics even if he got magicaly moved to Ul'dah. He would just have waaaaay to much work to keep up with really. Likely, the infamous 'the elementals don't want her to be healed' conjurers in Gridania would have a visit from the rogue.
Until we get more lore on them it really is impossible* to say if a character is going to follow the lore or not, unless they are preplanned to be a DRK that follows the blurb as the character concept.
*Well.. in my opinion.
