Char Aznable's wild shift in character between the end of Zeta and the beginning of Char's Counterattack can be directly pinned on Kamille Bidan's mental crippling at the end of Zeta and Haman Karm's actions in ZZ.

Char, who always had a rather strong protective streak, more or less pinned his hopes on Kamille as a key to the future. Instead he directly experienced the Newtype backlash of Kamille being mentally crippled, and subequently could no longer sense him. This convinced him that humanity was doomed to eternal conflict, unless it was forced to advance.

Still unable to get over his protective streak, Char then manages to extricate Mineva Lao Zabi, the last remaining Zabi and perhaps the only one who he doesn't actually seem to harbor any hatred towards, to Earth. But Haman just creates a double, which she uses to drag Neo Zeon into yet another war for personal power. This convinces Char he cannot trust the future to anyone else, even after protecting the ones he cares about.

Thus, we reach CCA with a Char who is fixedly convinced of both the need for forced human advancement, and that he alone must be that leader.