Misbehaving guinea pig?

i hav had my guinea pig for 4 and a half months, and hes still scared of everything. if i put him down he just runs away and hides, and never comes out of his hut when i call him, and is very wild. ive tried giving him treats when he comes to me but hes still afraid. on the other hand my friends guinea pig is really well behaved and shes only had her for 4 months too.