New GP Human Interaction

Question
Hi Jules:  We purchased two male GP's three weeks ago today.  Judging by size, the appeared to be very close in age, but PetCo couldn't give an exact age. The larger of the two (I think he is at least an adolescent) is very apprehensive to being held.  We have taken it pretty slow, but he still just wiggles to get down.  He seems to be even more apprehensive as time goes on. He also does some "nipping" at us even though we aren't doing anything but holding him. He is also getting really fat :) (yes, he is a male!!!)  We have been only giving fruit 1 to 2 times per week and mostly romaine lettuce and cucumbers for their fresh veges and we also free feed Vit enriched pellets and timothy hay. We also put the drops in the water. We let them out in a larger pen to get floor time. He still does a lot of popcorning as well as laps in his pen, but just can't seem to get used to us. My kids have been wanting GP's forever, and now they have one that won't interact well.  They are very careful and sit very still with him.  We have hand fed in cage and while being held.  He only gets the fruit when being held in hopes of positively reinforce the hold time.  So, I guess my questions are:
1. What can we do to make him want to be around us
2. Should we change his diet or is the weight gain normal for an adolescent male (our other boy doesn't seem to be gaining at the same rate).
Thanks for your help!!!

Answer
Dana,

There are some really easy handling tips to help you calm him down. He sounds like he is a little older then your other one so it is going to take him a little bit longer to warm up to you and the kids. Using these handling tips should help calm him down and get him use to you all.
When around the cage talk to him. That will get him use to your voice and have the kids talk to him to so he knows their voices too. Also when around the cage talking to him, put your hand in and let him smell it, that way he will learn you smell and be able to connect your smell with your voice. After he has smelled you, go ahead and pet him for a few minutes. That way he'll learn that you mean him no harm. Try also sitting in the pen with him and play with him, talk to him, and pet him. That'll teach him that your apart of the group and he'll calm down. Have the kids do that to, have them work with you in trying to get him use to his new owners and home. That way he'll know he is safe around all of you instead of just one of you. Also just give him love and attention, and soon he'll be a very calm lovable Guinea Pig.

Your big guy may just be putting on weight so fast cause he is growing, Guinea Pigs don't stop growing until they are about 1 year or so old. So he is going to start growing and fast. His diet is perfect so no need to change that at all, just so he doesn't get to fat try putting a few toys in his cage and play pen. Toys will keep him active and happy, try toys like, wooden tunnels, wood chew sticks or Guinea Pig chew sticks, old towels and wash cloths are good, balls to push around, and a few little stuff animals are great toys for Guinea Pigs. Just stay away from paper and cardboard as both contain things that are poisonous to Guinea Pigs.
That'll help both your boys to stay in shape, but keep them active and happy at the same time.

Hope this helps you out. Good luck with your little guys and enjoy them.
Jules