Pretty angsty I'm afraid. Also, I didn't quite know where to slot this one in.
Disclaimer: Leon/Squall is owned by SquareEnix, 'they' are owned by no-one...
Fake: make presentable or plausible; alter so as to deceive.
If he was to say that 'Leon' was fake, he knew people would agree.
They would point to his coldness, how he pushed people away so they didn't get to know him.
They would point to his anti-social behaviour, a typical sign of someone trying to get attention but not knowing how.
They would point to his aloofness, his gruff "Whatever", a mechanism that hid his emotions.
They would point to his stance, the folded arms that created a barrier between him and 'them'.
But those weren't the things that made 'Leon' fake. He was fake when he laughed, when he smiled, when he joked. Those were the things that weren't real, weren't an honest part of him.
They were the things that made him not 'Squall'.
They were the things that he did to forget.