You decide that while changing the body to suite your tastes would be good, Shirou as he referred to himself might not appreciate having a single eye, neither would the rest of the world. Most would fear you, though rightfully so, but unfortunately that is not something you can afford given your current state
Needed: 15 rolled: Roll(5d20): 20,12,3,5,12+Roll(1d10):5= 57 resounding success
The process is painless for both both of you and goes swimmingly, the boys hair darkens to the shade of red you desired, one akin to your own that is. and while you refrain from making his skin red it now has a little bronze in it to please you. His eyes are now an enchanting Sapphire the color of eldritch lightning. Altogether you are pleased with your work
In fact it goes so swimmingly that the changes you wrought have enhanced the boys features making it more prominent (Shirou gains trait Attractive).
This is irrelevant to you however as when it comes to what you look like, you have always chosen to appear with many faces and yet none at all. Perhaps one day you will match the emperor in that. But that day seems as if it is far off.
Retreating back into the boy's/your mind you find him sleeping fitfully, no doubt he is reliving the fire that has emptied him so, the scream, the cries of anguish, those waiting to be saved but never finding salvation. If you were at your full might you would have traversed the skeins back to before this fire started.
It is then that you managed outside to pinpoint the direct location of the feeling of evil, Maybe you should try to force this body to move, to try and find an eradicate it so something like this may never occur, that or you could collect it and study it.
[]Force yourself to move to where the power you are sensing is (note if succesful may or may not prevent the events of Heavens Feel or at least gain knowledge of the Grail War, may lock routes of being adopted by the Magus Killer though)
[]Continue to lie here motionless (Canon Choice can lead to Fate/Stay Night)