Have you seen the ending of CG season 2...? Suzu never wanted to actually kill Zero(except with the Euphy part, but he was heartbroken then), he just wanted him locked up. Spoiler: Suzu is also Lulu's(Zero's) best friend, he was again heart broken when he found out the Lulu was Zero and then at the very end of CG when they were finally getting along... Well just watch the last 2 eps of CG season 2.
Sorry, minor ramble. This is just my view on them