[He knew that would be difficult for now... Especially if Anew is yet to hear what "The Aeolia's Plan" really was. The Innovators, Innovades... Their true relationship together. It is the reason why he says the things he does. However, he did not want to overwhelm her.
Time will heal all. For now... for now, he just needed to be here. For her. Not as an Innovator, but as Setsuna. Her "little brother."]
... I will. I promise.
I believe in him as well. I am certain that he will do his best to aid your own wish. [And if Tieria feels the same as he does... Then, the Innovade perhaps only said those earlier as he wills to also aid understanding for everyone.]
[He trusts Tieria that much... And so, he has enough courage to say this—] I will not let them harm you or anyone ever again.