Why does my guinea pig run from me when I try to pick him up - even though he loves to be held?Answer: According to Guinea Pigs: A Complete Pet Owner's Manual by Katrin Behrend, "Guinea pigs are defenseless animals, and they must use flight as their sole means of survival. For this, nature has endowed them with speed and agility" (p. 41).
In other words,we don't have fearsome teeth or claws like some other animals, so our first instinct as a species is to run and hide if something seems like it could be dangerous. You're probably thinking, "But why would my little piggy consider me dangerous? I treat him/her well." I'm sure you do (you do read Cavy Savvy, after all!), but you humans are so much bigger than us that it's hard not to be terrified.
That said, there are some personality differences between piggies; some of us are more skittish, and some of us are friendlier than others. Sometimes we can learn to be less scared of you over time, especially if you feed us treats; on the other hand, some of us will always be fearful. The best thing you can do is to treat your piggy well, and accept them as they are, whether they become less fearful or not.
I could go outside, but I feel safer in here.