Why did the daimyo adopt him?
1) Was the lord having an affair with the characters mother?
2) Was he indebted to your characters father, or otherwise bound to him?
3) Was there a wise woman who appeared to the daimyo when he was a boy and prophecied three improbable things that would occur that would lead his family to greatness, one of which would be his becoming daimyo (he had two older brothers, so it seemed very unlikely), another of which was some improbable battle during an eclipse (which occured as she said, and the confusion caused by the eclipse helped the young lord to seize the initiative and win out over the demoralized and superstitious foe) and the third of which was the coming of 'the child who hides a fox's cunning beneath a human smile.' When the lord found a child who was both a fox and a man on his doorstep, he adopted it himself, hoping to complete the prophecy and bring his house to greatness.
What do the lord's other children (if any) think of their adopted half-sibling? Are there issues involving inheritance? Do the others resent his special status or treatment, or feel that he's given slack to do as he pleases, while they are expected to continue the family traditions and their every behavior scrutinized and criticized and commented upon?
What about other families within the clan? If the lord doesn't have biological children, does his sister have ambitions for her son to lead the clan upon her brother's death, and have dark designs for what sort of unfortunate accident will befall your character to prevent any sort of succession struggle 'for the good of the clan?'
How does this adoption affect the clan as a whole? Do other high-ranking families think that the lord is soft or sentimental or completely unfit for command because of his strange choice in taking in some unreliable creature that is not only not of the proper bloodline, but not even *human,* as his 'son?' Is his rule weakened enough that the family has devolved into infighting, with various sub-families jockeying for influence, under the tacit agreement that he's not fit to lead and that one of them will be in charge soon enough?
If your character, as adopted 'son' of a lord, is known as such, he'll no doubt be the target of assassination attempts by the gross and unsubtle, and, far more commonly, the target of people trying to get close to him to gain some sort of advantage or leverage over his powerful father. Some enemies will try to lure your character into publically humiliating or shameful behaviors, such as drunken brawls or public lover's quarrels with 'lantern women' or other things that will bring all sorts of shame and dishonor upon the entire family. Others will pretend to be your friend, and hope that he'll slip all sorts of unfortunate secret information to them, that their own families or employers can use to gain a social or mercantile advantage.
Depending on the nature of the characters relationship with the other members of the family, he might have more to fear from relatives than rival clans. Then again, if going with some great prophecy thing (idea above), the whole family might consider your character to be 'too important' to send adventuring, which could require him to run away, and conceal his identity, as his family are constantly seeking him to drag their 'lucky fox' back home to his gilded cage.
