Why is he such a stalker?

so me and my friend were at my grandmas house, when we saw my cousin. he stared at us the whole entire time we were there! and we were there for 3 hours! he took pictures of us and he creeps on my facebook page! i would have told him to stop but his mom and dad are SUPER protective of him so i always get blamed! hes 13! and he has fake teeth cuz they never told him to brush them and stuff! he creeps us out and stares at us! if i say anything, then I will be the "bad guy" for somethin he did! help me! what should i do!