MONACO — In what appears at first glance to be a simple, magnanimous act, a Russian billionaire is poised this week to return two Picassos, valued at $30 million, to the artist’s stepdaughter, who says the works, both portraits of her mother — Jacqueline Roque, Picasso’s second wife — were stolen from her.

The businessman, Dmitry E. Rybolovlev, owner of one of the world’s most valuable art collections, said in an interview last week that he bought the works in good faith in 2013, without any hint that there was a question about their title.

“I feel solidarity with her, especially because there is a strong emotional link between the portraits of her and her mother,” Mr. Rybolovlev said in the interview from his penthouse apartment here overlooking the Mediterranean.

But Mr. Rybolovlev’s decision is much more than just a chivalrous, expensive gesture. The man from whom he bought the portraits, Yves Bouvier, is also Mr. Rybolovlev’s adversary in what has become perhaps the largest feud in the art world today. And by returning the art in such a public fashion, he is drawing attention to their broader fight.