Disclaimer: I most certainly do not own. I just read and then borrow the characters.

Singularity.

One Dr. Watson was a new experience. Never had Sherlock Holmes found one like this before.

Watson, though like any other man in having his pride and self-belief, had from the very first moments of their meeting never been one to stubbornly contest what was logically explained to him. For this, and the fact that Holmes' elaborations were enough for him to grasp what was being said, the man was an utter singularity.

Flattery.

His hearty exclamations of brilliance were another matter to be considered. Watson didn't mean them as a form of flattery. He was too honest for that; his words rang too true.

What they were was a bit foreign to an unfathomed genius such as himself: praise.

Thoroughly.

His rapid examination of the mind and inner workings of this person could only be accounted to a momentary interest which was, quite clearly, only due to the intriguing difference he presented to Holmes.

Thus, Dr. Watson's singularity of understanding and discernment, paired with his lack of offered flattery, led to the thorough amount of attention given him for just long enough to have a decision made.

He was noteworthy and had the potential to become more than he was, but currently of no consequence as anything other than a useful companion to Holmes.