ADMIN - Help the mun out?
Mycroft notices things. Unlike his brother, though, he does have the tact to keep from blurting these observations out loud.
Unless he thinks he can benefit from it, of course.
For the most part, he'll just calmly work his observations into conversation, often giving the impressing that he can read your pup's mind. Mycroft is, quite plainly, creepy. But in order for this to be pulled off, he has to know what your pup is thinking, which means that I have to know what your pup is thinking. The easiest way to do this is simply putting relevant information in your tags. I also tend to go through profile pages to see what I can pick up from there, so detailed profile pages are ♥.
Also, OOC communication is greatly appreciated with this one.
Strictly speaking, what Mycroft does is cold reading -- making note of microexpressions and body language, so he's not always 100% right. There are things that he misses, or misinterprets, but he's more than happy to let you correct him and then turn it around to make it seem as though he had it right from the start.