Bringing Davina and Lilliana isn't something that he was pressured into.
He needed them.
Devo and Amanir were now in the Mortal Realm after having their aptitude upgraded. Both of them are going to help Adhara survive whatever situation she is going through under the deadly hands of Kaiser and Meloriana.
Despite his desire to help her, there was nothing he could do, even with the System's aid.
It was out of his hands the moment the veil was enacted.
However, it was easier for him to accept the truth when he saw how Adhara looked at him.
She wasn't helpless, but determined.
In a way, she was telling him through her gaze alone that she would survive and cause him no pain.
And for once throughout their relationship, Rex believed her.
Something behind the silvery pearls of her eyes convinced him that she could handle it.
