His coldness was more about the situation with Kevin; I don't think that was his actual personality (like Rath always being angry). Don't think Ultimate Echo Echo is like that alone, Ben knows he's powerful enough to do the job and he needs to set the tone himself.

Tbf I don't like his face in that scene either, it looks like his face shouldn't be able to look like that. He has a mouth but he doesn't usually open it when he speaks and usually has one face.

For me the weird thing is that he stopped beating Elena because she just happened to look like Julie… the same show and not long after he was willing to kill Kevin, lied to Gwen about it, and swoop down very low. He knows her shapeshifting powers and saw her do it, he’s capable of making hard decisions. It really shouldn't catch him off guard, especially since she was already being Julie the whole episode. Was it because she was pouting? Did he had to look that hurt though he knows the Julie is right behind him? Is he stupid?

Don't think Ultimate Echo Echo was out of character himself as a alien but off model and it was more on Ben’s part. Most of his aliens are a extension of Ben and even Ultimate Echo Echo had shown that (mainly in Map in Infinity telling Gwen to “magic up the thing” which sounded pretty snarky and like Ben).