Lenny is a normal person that lives in Scrapheap. He looks over the brahmin that are used to fuel the generator. Thinking they are his "friends", he tends to sleep in their pen at night so that they do not get scared, causing him to smell like brahmin dung. According to himself, he does not like the Fools because they are 'mean' to him.
If the Vault Dweller asks about buying one of his brahmin, he replies saying that he could not possibly sell his 'friends', and that he is not a slaver. This statement makes him upset and will not talk to the Vault Dweller.