For some reason, I can see Alison being okay with that ego due to Julian having the money and powers to back it up. Like... every one's lower than her, unless you're cool enough. And the idea of someone being there to be like "embrace you're mutantism" (it's a word) is awesome.
I admit it. I'm a slave to the lulz. All I can think is it had something to do with being on the same team.