Venom is a Darkspirit, a malicious demon-like creature that usually cannot exist without a host, they vary in strength from simply making the host a little sadistic to being capable of total possession of the host, this was the kind of Darkspirit Venom was, his host was Shade. Venom was becoming increasingly more powerful and his control over Shade had become nigh permanent, something had to be done lest Shade be forever lost. During one of the extremely brief periods Shade broke through Masque performed a separation ritual that successfully expelled Venom however, he did not perish once wrenched from his host as was expected. Venom had become so powerful Shade was no longer necessary for him and the separation only made him stronger, with no good side to hold him back his power grew exponentially. Eventually Wraith and Mystique managed to get a collar around his neck (which I forgot to tell Sharella to add) which weakened him and can only be removed with the Crescent moon necklace around Mystique's neck, hence Venom harbours a particular hatred for her as she is holding him back from Demonic Godhood. Venom takes any opportunity to cause pain and suffering but he is fiendishly clever and because he himself cannot enter the refuge to kill Mystique himself he sends others he coerces or outright possesses to do it for him.