(CNN) The Trump White House is at once decidedly leaky and totally unknowable. We know there's lots of jockeying and infighting among President Trump's top advisers, but what we don't really know is what specific roles each of them play or who, at any given time, has the President's ear.

Enter Eric Trump. The second youngest of the male Trump offspring, Eric gave an interview to The Telegraph newspaper in which he offers a telling glimpse into the role his sister, Ivanka, plays vis-a-vis the other advisers in his father's orbit.

Here's what he told the paper:

"Ivanka is by his side in Washington. She is not involved in everything. I think she comes and goes with issues she deeply cares about but when you get to a certain level of power a lot of times, and you see this in business too, a lot of times people will say yes just because you happen to be the boss....

...I think it gives you a sounding board who is a little bit more unconventional than the 37 people that might happen to be standing round a table at that one time who just want to appease."

Totally fascinating, right?

What we learn from Eric Trump here is that: 1) Ivanka is the person in the White House who can tell her father "no" and 2) her installation as a formal adviser -- with a West Wing office -- might well be in reaction to the family's concerns that Trump wasn't getting the right sort of advice from "37 people that might be standing around a table at that one time who just want to appease."

On one level, this isn't terribly surprising. The President has made no secret of his affection for his eldest daughter. And, say whatever else you will about him, Trump is deeply loyal to his family -- and always has been.

Then there's the fact that Ivanka is, without question, the most popular member of the Trump family in the minds of the general public. She's also widely regarded -- and also widely mocked -- as the leveling or moderating force in her father's life and on his politics. Many Democrats' only solace in the wake of Trump's victory was the fact that Ivanka would be moving to Washington and would, theoretically, be by her father's side when he made big decisions.

But, seen against the backdrop of Trump's first 80-plus days in the White House, Eric Trump's comments about his sister's role are far more intriguing.

There's little question -- public posturing aside -- that Trump knows he hasn't had the start he envisioned for himself. His travel ban -- championed by chief strategist Steve Bannon -- is mired in legal appeals. The health care reform legislation went nowhere. His approval ratings are the lowest of any president ever at this early date in a term.

Change is required. But, while the media tends to focus on whether Bannon's days are numbered -- in addition to the travel ban debacle, he's been feuding with Ivanka's husband Jared Kushner -- Eric Trump's comments suggest that the addition of Ivanka is the change their dad needed.

The question always with Trump is not only who he listens to but also whether he listens to anyone at all. As in, he has surrounded himself with a panoply of people with lots of views on issues. They tell him what they think he should do -- and then he just does what he wants anyway.

Ivanka, presumably, is someone who Trump actually listens to. And, per Eric, she is also someone who can tell their father that something he is planning to say (or, closer to home, tweet) is a very bad idea -- and he might actually respond positively.