Claire's comments about Charlie in her diary.
Claire kept a diary, in which she wrote frequently. She wrote down her dreams in it, including the one in which her baby was stolen. ("Raised by Another") After Claire was kidnapped by Ethan, Sawyer made fun of Charlie by mockingly reading an entry that claimed Claire was getting tired of "that has-been rock star". When Charlie read the diary, he saw a packing list for her trip and that she wrote:
I realized I really like Charlie. There's something about him that's just so adorable and sweet.
He also saw that she had written down her recurring dreams of a black rock (though it appeared to be of an actual black rock, not the ship). ("Special") After she returned to the survivors' camp, she tried to use it to recover her memories by writing them down ("Homecoming"), but ultimately got help from Libby to remember what happened to her in the Staff. ("Maternity Leave")
"I HATE HIM" and blurred text in Claire's diary
On the page Charlie views before the one that reveals Claire's feelings towards him, the words "I HATE HIM" are mysteriously written on their own, under what appears to be a list of things Claire misses from the outside world. Also on this page is a word or short sentence that is blurred out. What it means is unknown. ("Special")
This article/section contains information that was shown or released via an official source such as ARGs or extended media (video games, books), however it has no canonical merit to the overall Lost mythos.
The deuterocanonical website Oceanic-air.com has an Easter egg wherein a screencapture of this diary is seen when clicking on Charlie's seat (since he was the one who would later recover it). In it, the picture of her ex-boyfriend Thomas is scratched out. An excerpt:
So, waiting at the airport is always such fun, not. Toilets are really really gross too & I have to pee like every 10 seconds. Stupid baby, I shouldn't say that... Hope to sleep as much as I can on the plane, so nervous last night. I didn't sleep, couldn't. [drawing of a tic-tac-toe game] I hate the steward dude at the desk thingy before you get on the plane — "no you may certainly not move to a 'higher' class — we are too full." & such an ass about it, bet he's full of it too.