alpha male and kitten behavior

Question
WE have a four year old neutered male, and a six month old  not-yet-neutered male kitten, who arrived to us (found him abandoned under a car)at two weeks of age last summer. (We have had the four year old since he was about 6 months and old,also) Up until now, no behavior issues with the two, lots of play fighting and wrestling, but no serious actual aggression.
A couple days ago, out of the blue, the kitten walks around with his butt up in the air, rolls around on the floor exposing his belly, and makes very strange mewing noises while he is doing this. He also will lay on his side, holding one leg up in the air, then switches sides and does the same thing with the other leg.Sometimes it goes on for about 30 minutes straight. The older male cat isn't even around sometimes when the kitten does this. All in all, it happens on and off for a total of about two or three hours over a 24 hour period.
I called my vet who said the kitten is letting the older male know that he is submitting, and letting the older male be the "alpha male" permanently.
But now why, all of a sudden?  And how long will he act like this, I feel so sorry for him, he seems so, so , hormonal (for lack of a better word, LOL), it makes me sad to see him like this.  When he's not doing it, he is his regular happy self. ANd the older cat, if he is in the room while this is happening, just stares at him, as if to say "What the heck are you doing"? Sometimes, rarely, the older guy will walk over and lick the little guys head while this is going on, and once he bit him lightly on the back of the neck. ANd the kitten just lays there and does nothing in return. In the past, if the big guy did something like that, the kitten would swat back, and start playing, but now, he is just being so submissive.
How long do you think this will continue? This kitten is acting like a female cat does when she is in heat. Do you think my vet is right about what is happening?  Their names, by the way, Rusty is the older guy, and Chester is the kitten. Both orange tabbies. Thanks.

Answer
Cindi,

My opinion is that your little 'boy' is becoming a 'man' and is having 'confusing thoughts and feelings'. Rusty biting him on the neck is a good indication. As soon as you get him neutered you should see his personality go back to normal within 15-30 days. I would get it done as soon as possible.

He may be acting submissive, but I would say it was more the sexual type of submissive than the aggressive-related/fear related submission from an alpha cat.

Tabbi