Bit of backstory for him:
He's a human who in a certain timeline was raised by Sans & Papyrus. He grew up believing he was a monster, and has no ears, but can "hear" people's voices by listening to their souls.
It's the best backstory I came up with for this guy. XD

Mettaton's fine. XD
I'll just be using Rene, so no worries, unless you want me to be someone else too. ^u^

(Fine with me, IDC. XD)
Rene: *Sitting on the floor eating popcorn, he looks over at Sans & Frisk and giggles* That's cute...
(Craaa.p...GTG to bed, I'll reply tomorrow when I get home... It'll take about 3 hours to meet with my mom, then another 3 to get home, so I may be home by 4 or so. *Hugs* Sorry, see you tomorrow! >n<i)

Rene: *Smiles at his adoptive brothers, and looks at Papyrus curiously* Hey Papyrus? When is Mettaton coming over?

(Okay. ^u^ I'll reply to it.)
Rene: *Laughs* That was quick. Hi Mettaton! *Smiles* ^u^

(Obvious Sans. XD)
Rene: *Chuckles, then looks over at Sans and hugs him*

(Dramatic 100 XD)
Rene: *Chuckles* I had a funny joke to tell you, but I forgot what it was...

(They're having a baby aren't they? XD Somehow?)
Rene: *Trying to remember the joke*
(I literally thought of a funny joke for Rene to tell Sans, but forgot it. XD)

Rene: *Chuckles* Heh...it was a REALLY good one though. You'd be laughing really hard if you heard it, I really think you would...
(No worries, I know better. XD)

Rene: *Laughs and sighs, he opens the door to go outside and keep Sans some company* Let it go Papyrus, don't hold it back anymore that you love his jokes! *Closes the door and laughs* That was kinda good...
(Do you get it? It's a really bad joke though... -Also it's not the joke I couldn't remember.- XD)

(I was watching a video called "TerrariaTale", where Papyrus & Undyne were drunk, and at one part Papyrus started singing "Let it go". XD So I had to think of something.)
Rene: *Shivers* Man...it's really cold out here...!

Rene: *Smiles and nods* Alright, c'mon Sans! ^u^ *He goes inside*

Rene: *Smiles at Mettaton, then giggles when Sans falls asleep* Awww, how cute...!

Rene: *Smiles, then remembers something* Oh yeah! I forgot to wrap my present! Cra.p...! *He hurries to his room, slamming the door a little by accident*

Rene: *Paper ripping can be heard from his room as he wraps his present, he takes about 15 minutes just to wrap it all, he finally comes out of his room, trying really hard to keep his balance as he carries a big present down the stairs, it's almost as big as himself* Rrgh...why did I get so much...

(It's okay. I thought you were drawing something. XD)
Rene: I'm fine! I'm almost there...*He carries it down the steps and moves it to the middle of the room* There... *There's a tag on the present with Papyrus, Frisk, Sans & Mettaton's names on it*

Rene: *Smiles* Well, I got all of this stuff for each of you guys, and I didn't want to put them all into separate boxes, so...yeah. Every gift inside is wrapped up in different colors so you guys know which ones are yours, so...go ahead and open it if you want! ^u^

Rene: Huh? Okay...Guess I better wake up Sans...

Rene: Yeah...He's Mettaton though, I'm pretty sure he's okay. ^u^