Because Ace is just the alter-ego of Nic, who is the alter-ego of Alex, and Jace is the alter-ego of Jason, who is Alex's little brother. Being alter-ego's, they're way too similar but way too different from each other at the same time. I don't know how else to explain it...
I'm never what I like I'm double sided And I just can't hide I kind of like it When I make you cry 'Cause I'm twisted up, twisted up Inside
"Do not try to be pretty. You weren't meant to be pretty; you were meant to burn down the earth and graffiti the sky. Don't let anyone ever simplify you to just 'pretty'" — Suzanne Rivard