Should I be concerned?

Question
I am fostering an approximately year and a half year old male Balinese.  He was rescued from a breeder about a month ago and neutered at that time. He is currently living in a sanctuary room in my house (for 2 weeks). I am in the process of introducing him to my 4 other cats.  None of the cats seem to be upset about him- no growling or hissing. However, I am a bit concerned about the behavior of my neutered male who is about 21 months old.  Ringo is a very friendly, outgoing cat. Ringo is also a very large cat, around 16 pounds.  Wally, who is just under 6 pounds, has been out of the room (with the other cats not able to access him) and is getting used to the rest of the house.  The cats all seem to be reacting well (or rather not really reacting to the new cat).  I have let Ringo and Wally have brief closely supervised contact because Ringo seemed receptive and they have been playing under the door since Wally's arrival.  Here is my concern.  When Ringo was introduced to Wally, he sniffed his nose but then mouthed his neck a couple of times.  He then licked him on the head and proceeded to give Wally's backside a long smell.  Wally did not react defensively to this. In fact, when Ringo is close to him he purrs. I know cats can purr when they are very stressed, but he does not act afraid.  Is this normal male to male behavior that I should or should not be concerned about. I've kept their meetings very brief and watched for any fixated eye stares etc... Wally seems relaxed and content around Ringo.  

Is Ringo going to eat Wally?

Answer
Susan,

No, Ringo is not going to eat Wally. Ringo is just showing affection to Wally. Some male cats are very maternal.

Everything is new and confusing to Wally and he is purring because he is finding comfort with Ringo.

It sounds like they are getting along fine and you shouldn't have any worries.

Tabbi