Sarah: Nothing is wrong with her!
SORRY FOR THE INCONVENIENCE, I didn't know Sarah tells her age, I was meaning to explore the other options later. Sorry. >.<
Okay! So, I've been reading posts about Sarah being mentally challenged and having autism, down syndrome, ect. But people don't know what being isolated in a cabin hiding from monsters can do to a child.
I've have some people say she's not a child, she's 15. But I mean come on, the way she talks doesn't sound like a 15 year old. Look at Becca, (Shel's sister from 400 Days) she's around the age of 14-15 and isn't high pitched and child-like at all.
I'm getting off topic.. 
Back to Sarah, her being an 11-12 year old (estimate guess) with no other children, of course once she sees an opportunity to make a friend, she'll make one. But being isolated in a cabin and in fear everyday from monsters (walkers) can affect a child. Clementine wasn't as affected at the Motor Inn because she had Duck, a friend.
Hope this clears some stuff up. I don't think there's anything wrong with her mentally, just a little lonely.
Comments
Sarah is 15......
She is 15. And down syndrom? Dafuq do you even know what that is?
15 year olds don't do pinky swears, do they?
When was she confirmed 15?
I wouldn't have said it if I didn't, and when was she confirmed 15?
"A pinky swear is forever!"
5 seconds later
Yea....umm we're not friends, I just wanted peroxide for my wound :P
Sheltered girls maybe do that. Who knows. Maybe I test it.
When was she confirmed to be 15?
Pinky swears are for life.
And she confirms herself to be 15 if Clem says "We're not the same age." As for the topic at hand, there is definitely something...off... about her. Maybe that's due to the isolation, maybe it's due to something else. But all I know is that I'm going to be keeping an eye on her.
if you choose to say we're not the same age sarah tells you she is 15
She tells you lol.
When she stood up I was like "Damn! You are tall as shit!" Compared to Clem lol.
If you have Clem say "we're not the same age" then Sarah will say something like, "Really? How old are you? I'm 15."
Sorry guys for Sarah's age, I haven't explored the options yet, don't pay any attention to the age bit.
It could also be that Clem seems older to Sarah because she's been through some shit. And Carlos did say something like "she doesn't know how bad it is" so it could be that she's just been sealed off for so long she's regressed a bit?