The look Allison gives him at that statement is a strange mixture of fondness and exasperation, because for one, she can't actually say any words. The lined memo pad is sitting on the coffee table between them, and she hasn't reached for it. Instead, what she reaches for his him. She gestures once with her hand to come closer, before holding out her hand for him to take.

She knows that Diego has had a day. They've all had a day, between Vanya and everything else. She also knows that she doesn't want to be alone, given the Day that has happened, and if Diego is here, than Luther probably won't hover.

Using one brother to avoid the other is probably not the best plan, but for now, it's the plan she's got and it seems to be working.