As you sit besides Thomas' head you think you might as well go through his mouth since its so close by.
You slowly move yourself up Thomas' chest and sit tight right before his chin. "Ok. Here I go." you think. You slither up Thomas' chin, move into his mouth and further down his throat. Thomas, who is now unable to breath starts to spasm a little as he can't get any air anymore. Thomas then suddenly jumps up and looks around him to see what is happening. He notices the green slime slithering into his mouth and down his throat and tries to pull you out. He cannot get any grip on you and you continue to move the rest of your slime into him. Thomas is becoming weaker and collapses on his bed. With Thomas out because of him being unable to breath there is nothing stopping you from going down his throat anymore. You move the last of your slime into your little brother, and everything goes black.
A couple seconds later you wake up gasping for air. You look terrified as if you had almost been choked to death. As your heartbeat lowers you realize you don't have your slime perspective anymore. "YEA" you say softly in your new voice. "Let's see who is the pretty boy now Thomas" you say to yourself.
Since Thomas doesn't have a mirror on his room, you'll have to go to the bathroom. You can't wait to see your little brother's face after this. You get out of Thomas' bed and open the door of his room. You quietly walk to the bathroom and lock the door from the inside. You look into the mirror and see the pretty face of your little brother stare back at you. "Hell Yeah" you say as you move your hand through you new haircut. Even thought Thomas is only 3 years younger, it might as well be 30. "Being Thomas feels awesome." you think and you notice a bulge growing in you pants.
"Well... Why not" you say and you start to remove your pajamas. You strip yourself until you only have your underpants on. You can clearly see the shape of Thomas' dick growing in the pants. "Let's see if you're just as pretty down there" you say and you pull down your pants revealing Thomas' 6 inch cock being fully erect. You look at yourself in the mirror. Thomas looks back with a dirty smirk on his face. "Here we go" you say as you start stroking your dick. It doesn't take long till you start feeling fluid to leak from you cock. "Uunnggg" you moan as you are filled with pleasure. You decide to make things even more exciting by putting a finger up your new tight butt. "Aahhh..." you moan and stick some extra fingers up there. Then the moment arrives and you quickly grab a dirty piece of underwear from the pile of dirty laundry next to you. You move the pants over your dick and come. "Oh.. Yeah...." you say in a horny Thomas voice. You use the underpants to clean your dick and throw them back onto the pile. You look at the pants, now covered in Thomas' cum. You recognize the pants to be the ones you wore yesterday in you own body. "Heh heh" you laugh as you think about what to do next.