Given that Reeves is drawing inspiration from the 1960s series, Robin's appearance is somewhat expected.
I mean, he has already adapted the main villains in the first film
(Penguin, Catwoman, Riddler, and Joker)...
Heck, even that damn red phone was there!
So much of The Batman and The Penguin are about parents and their effect on us. The Waynes, Alfred, Falcone, Francis. This is such a natural extension.
Yep, I remember discussing those observations when the film was released.
Thematically, the groundwork has definitely been laid for this Bruce to eventually explore the parental figure.
If it really happens, it won't come from nowhere.
Ironically, I just saw
Superman two days ago, and I feel like I could sense the outlines of a similar theme—that of “family”—in Gunn's DCU. There's Superman reevaluating his parental heritage, Peacemaker's relation to his father, Waller and her daughter...
Just before this rumor about Robin in
The Batman Part II broke, I was about to post about how it seemed more and more logical to me that Gunn would want to bring Damian into the mix, beyond the fact that a child assassin character might inspire him stylistically.
It really looks like, when it comes to Batman, Reeves and Gunn may had similar ambition thematically.
In any case, it's pretty fresh!