Sakura's Links
She tried to use him once to try and gain influence and power over the Realm of Hearts. While she was planning on backstabbing him, she herself got backstabbed and she learned the awful truth of who the Mad Hatter really is. Now she's terrified of him and even sometimes has nightmares about him. However, she won't ever admit this to anyone and even though she knows he's incredibly dangerous, she won't ever tell anyone in fear of him going after her and snuffing out her life.
A woman of whom he knew was using him, but he was also using her. He never loved her or even enjoyed her company, and he backstabbed/dumped her shortly before she was banished from Wonderland, never to be seen again. He hopes she's dead.