Knuckles is the character that gets killed the most in any other endings (other than the true ending). Butt-Monkey: In Sally.exe Whisper of Soul.Exeller of all people actually saved Cream from being killed by a fully corrupted Tails Doll by decapitating him, but for a different reason (he needed the Chaos Emerald, and Tails Doll is not subservient to Exeller at all). In an alternate version of Amy and Cream duo run.Subverted, as Exeller's immortal and not only he's unfazed from being shot, he (inadvertently) killed Amy in his attempt. He recovers just in time to shoot down Exeller while the latter has her immobilized. If Robotnik's alive in Amy's solo ending.And in Eggman's solo ending, Alice saves him from a pursuing Exeller and teleported him near the Master Emerald. Alice will save one of the female protagonists from being killed by Exeller's slaves if one of the three have been killed.Corrupted Amy will save her by destroying Tails Doll, but plans on killing her later on. If Cream left Tails Doll, Amy or Tails will show up to thwart him from killing her upon confronting her in Volcano ruins.Tails Dolls first shows up to rescue Cream from Execun (either from escaping from Exebark, or from an Execun-disguised Vanilla).If the Forrester is already killed earlier, Exeller will kill Amy without problems. The Forrester shows up to save Amy from being killed by Exeller, enabling her to escape his grasp. Back from the Dead: Metal Sonic previously thought to be destroyed by Exeller from Spirits of Hell makes an appearance in Knuckles and Amy's duo ending and the True Ending route where Amy personally fights it.His lackey Execun even more so as unlike him, he fully embraces his psychotic behavior who takes pleasure in killing others in brutal ways.He only shows his psychotic side after Laura's death, and even then, he still is shown to deeply care about Alice, as seen in the Crazy Amy ending if Tails tells Cream Robotnik killed Amy's parent on purpose.
It also is a downplayed case: because of some Laser-Guided Amnesia, he was mentally stable for a while, his teacher even stating Exeller has a perfect attitude.
Justified as he is a Zero-class Highest who are noted to be inherently psychotic, which only boiled over after his and Laura's death. In some cases Exeller will simply kill Amy outright since she's no longer useful for him.
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Artistic License Physics: Despite being a stuffed toy without an endoskeleton (his only robotic part being his head which serve as his power core), Tails Doll is capable of moving his limbs, and lifting things and people (like rockets and Cream and Tails).