I'm more than a hundred percent sure that Delta will have almost no reaction to Morty. By the way, I’m not sure that he will even see him right away.
If Morty doesn't do anything to him, then Delta will simply ignore his existence. But if Morty bothers him or tries to steal something, then Delta will most likely perceive him as an external irritant. And he will try to neutralize him.

The situation with Prime is more interesting. Prime is not perceived by Delta as a threat or anything because Delta is convinced of his own superiority over him. I think that if Prime does something that increases Delta's competitive spirit, Delta will move to attack and possibly humiliate or kill Prime.
In general, Delta is quite indifferent to everyone, but after meeting Prime, Delta will probably decide to do something else in his life. And this "other" is the idea of capturing different dimensions. Capture or destruction. This is something from the category of “If this sucker did something bad, then why can’t I do something like that...”
That is, Delta will not have a specific goal if he starts doing this. He will do this “Just because”, will begin to make new discoveries in the field of his abilities and will eventually take action. I think that over time, of course, he will find the meaning of his actions. This meaning will consist in self-affirmation through the oppression of other types of life, their dimensions, and so on.

So don't let Delta meet Prime.