Lord You Know Who 
"[@Background Pony #D816":](/images/2241560#comment_8732444
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Zeta is an Obscurial, a cosmic being of the same race as Dormammu and the Entity.
His plan is to open the portal to the Dark Dimension to free Dormammu (ie. finishing what Kaecilius started).
And of course, Marller is a first class demon.
No matter how "prideful" Adagio may be, she's human now, so Zeta is higher on the villain food chain than she is. Besides, her plan is to rule alongside Zeta and Dormammu, so serving Zeta benefits her in the long run.
Also, Zeta knows the Winter Soldier Spell ("longing, rusted, furnace, seventeen, homecoming, daybreak, nine"), so if Adagio refuses to serve him, Zeta can FORCE Adagio to serve him by making her into a Winter Soldier.
Zeta is an Obscurial, a cosmic being of the same race as Dormammu and the Entity.
His plan is to open the portal to the Dark Dimension to free Dormammu (ie. finishing what Kaecilius started).
And of course, Marller is a first class demon.
No matter how "prideful" Adagio may be, she's human now, so Zeta is higher on the villain food chain than she is. Besides, her plan is to rule alongside Zeta and Dormammu, so serving Zeta benefits her in the long run.
Also, Zeta knows the Winter Soldier Spell ("longing, rusted, furnace, seventeen, homecoming, daybreak, nine"), so if Adagio refuses to serve him, Zeta can FORCE Adagio to serve him by making her into a Winter Soldier.