how did aranea mind control gamzee into giving her the ring of life? i thought she could only control trolls lower then her on the hemospectrum

Aranea and Vriska’s mind control powers work on impressionable trolls or trolls with low self esteem, not just trolls lower than them on the hemospectrum. Aranea has had billions of sweeps to hone her abilities so it’s no surprise she was able to control Gamzee.