So i was pickpocketing random citizens of Riften and i get to Aerin and he has a necklace and ring of major pickpocketing

So like is he secretly stealing from Mjoll or is this just random?

that's funny, but it's just a coincidence of random loot.
Alvor at riverwood can have a ring of pickpocketing when he offers to let you take whatever you want too, for example.

pretty big coincidence for him to have both a necklace and a ring of pickpocketing though.

Maybe Aerin is trying to level up so he can get the perk to remove people's clothes.

I bet he has something he'd like to reverse pickpocket onto Mjoll

http://chocolatesyrupywaffles.com/wp-content/uploads/2012/02/IF-you-know-what-i-mean.png