Stepping up, and rebeliously taking her place in the spotlight may be just the thing. ("He wants a Giant? I'll show him I can do a Giant!!" i.e Put HC is his place though actions. )
This is just what Little Monkey would do, but big DD is not like that.
As for HC's change in style, etc.this happens periodically and he has done this several times before. Each time, big DD would get upset about it. It was always short-lived.