Ever since the army arrived at Eclanor, Felix and Astra were plotting to get their revenge. Thus, teaming up with Frazer came naturally, and so they helped each other for mutual benefit. However, since Amedith's suspicion was still heavy on them, they decided to poison themselves as well with the food by bringing the same meal to their tent to share with Hilma.
However, to avoid the worst effects, they suffered through the initial effect of the antidote that only made things worse for them until Amedith was done checking up on them. Past that, their bodies healed swifter than anyone else; at the same time, the suspicion was laid off them. Their ultimate plan? To backstab Raven and his party members once the fight with the demon general was over. Weakened by the poison as well as tired from the fight, it would have given them just enough of a chance to drive a poisoned dagger through nearly everyone's heart.
