[JoeyP]

A new puppies interactions isn't always telling of what they will be like later on
The main thing that I would be concerned about is that his shyness isn't anything that is Physical ... because pain or discomfort will be shown in a dog's demeanor

As far as the runt of the litter goes
I have had many dogs in my life and the ones that were the most dear to me were the runts of the litter
I don't know if it was because of their small size or because they usually are smarter than their littermates
they need to be sometimes to get what they need
but they are often closer to their human counterparts
and I've noticed that they always have a better personality than their brothers and sisters
BUT
They sometimes have more health problems at the same time
so if you like this little guy
have him checked out first