Nice. I like your choice of theme, you apply it creatively to both strengths and weaknesses, and there's a variety of material to work with.
My main criticism is that it ties together a lot of elements which are not really related to each other. It's better than having technique-copying eyeballs that can set things on ever-burning fire, summon chakra mechs or rewrite causality, but it comes across as "if it involves patterns, you can do it", which isn't quite how sane Bloodline Limits work. Compare the Byakugan: "We have super vision, and because we can see your chakra, we can see how to shut it down", as opposed to having a variety of powers relating to the general concept of vision.
(It says much about the Narutoverse that I have to specify "sane", as distinct from the likes of the Rinnegan.)
It also has to be said that the benefits err on the practical side while the flaws err on the social/roleplaying side. (Of course, the personality flaws would probably be less obvious to the players if they encountered a Kakero NPC.)
These two key features do make it broken in my opinion. If I were to introduce this Bloodline Limit into MfD, I would limit the number of positive features to two or three, and the negatives to one or two, and make sure the negative features come up regularly and influence the PC's capabilities/behaviour.
RE the Frozen Skein, I don't think the overlap is strong enough, or at least the Shattered Heart's features could be pared down to those that minimise it. It would also have interesting interactions with certain worldbuilding features that have yet to come into play.
I know the shape that this bloodline ought to take, and it's definitely narrower than "if it involves patterns, you can do it." It's very specifically about being unable to not notice a certain kind of systemic failure.
Let me try and pare it down by describing a pile of limitations that I have in my head but maybe did not express very well:
- This bloodline does
not do things like "notice the flaw in your opponent's armor as they approach", "notice the explosive tag you saw is nonstandard", etc. It specifically detects flaws in
environmental or
behavioural patterns
.
- The
one exception to this is that you can use it to detect flaws in
yourself or
your own work. (You can notice that you drew this seal blank wrong because you're intimately familiar with your own work, and it's
different from how you do it. You can't do that for anybody else unless you have been making seals with them for literally
decades - that's how long it takes to develop an instinctive understanding of how they do things.)
- Using this bloodline requires active exploration and observation of a living environment. You could
theoretically apply it to running a spy network or other organization, but only to the extent that you had face-to-face interactions with your subordinates.
With regard to manufactured objects, it will tell you about their
purpose and
maybe a little of their history - how they
fit into their environment, in other words. It won't tell you if they're properly made or not unless you've already built one yourself. (See the exception above.)
If you have a dozen bits of someone's personal belongings, it can tell you a little about what kind of person they are - their habits, inclinations and everyday desires. Things they care about a lot and handle often are more likely to give you useful information.
If you have a
living-space kept by someone, their
home, that's the best case possible. That kind of deeply-interacted-with environment can tell you about their plans, their values, and maybe, if you're lucky, even their secrets.
If you spend about a day talking with someone, or about a week observing their daily life, you can get the same kind of information a close examination of their personal belongings could give you.
If you spend about a week in close contact with someone, or a month observing their daily life, you can start getting the kind of details that their home would give you.
You can use this to "detect lies" by noticing when what someone says goes against their own nature. That doesn't strictly mean they're
lying, though: it just means that if they did what they said, they had to force themselves to.
- This bloodline will not warn you of natural hazards. Avalanches, Chakra beasts, storms, sucking tar pits, and other things that are inherent parts of the environment you're in don't ping as "disturbances" to it. Notably, this means it will
not detect traps that are part of established fortifications, regular guard patrols, etc. (Those traps and guards are
right where they belong, thank you.)
- This bloodline will let you know what you
should do. It will
not give you the ability to
actually do it. This is particularly relevant to the "immersing yourself in a social role" application: just because you know what you
ought to be doing does not make you necessarily capable of suppressing your ninja reflexes/boiling emotions/etc.
With regard to the application to stealth, this bloodline does not make you inherently more stealthy: it just tells you when you fuck up. That means you can
train for stealth faster, but if you
haven't it'll just hurl a constant stream of useless criticism at you.
Infiltration specialists
might be able to use it to realise when they've been detected, but that would be a specialized technique, like Roki is to the Iron Nerve.
- Seriously, you do
not want to be on the front lines if you have this bloodline. I would expect you to be making Resolve rolls against shifts of mental stress whenever anybody on either side of the fight suffered a Consequence. Being in a disaster area or major battle might be outright incapacitating without use of Fate Points.
Summary edit:
This bloodline lets you ask the question
"Does [fact X] fit as a natural part of [natural pattern Y]?", and get a true yes-or-no answer.
If Y is "my current environment", or "me", you are able to ask the question without spending an action and/or Fate point.