It's like when father comes home and is jealous because mother has given Kaname-oniisama attention. Suddenly he pouts and wants to switch positions. Then mother teases him relentlessly.
[Offhandedly telling embarrassing stories about her parents.]
Or the time mother told him she was weary of the married life and father got all panicked. [She's heard so many stories.]
It's cute, right? [Poor Haruka... but see? Family being silly! That is the comparison.]
It sounds like both you and your brother have a great relationship.