Harriets brother?

[Bluespace]

I’ve no idea! Any suggestions welcome please

Arthur, Elliott, Oscar and Oliver all came to mind, but are all popular.

Are you looking for something a bit more unusual?

Harriet and

James
Oliver
Ben
Thomas
Alexander

Edward
William
Oscar

Samuel

Edward/Teddy
Theo
Alex
Owen
Rory
Arthur
Toby

Nathaniel, Tobias, Oscar, Josiah, Alistair, Lucian, Victor, Nicholas, Sebastian, Tristan, Guy, Luke, John

Trying to avoid the v obvious ones, though I see Oscar is popular!

Simon
Mathew
Cameron
Fraser
Callum
Saul
Niles

Freddie

Harriet and Tobias

Peter

We have Harriet and Benjamin

Thomas
William
Benjamin
Charles
Edward
Frederick
Nicholas
Oliver
Peter
Robin
Arthur
Samuel

Caspian and Harriet are very happy children.

Guy

Harriet is quite classic and Austenesque for me, so I'd look at similar classic boys names she used too (although I personally like Hugh with Harriet as well), such as :-

Edward
Frederick
Edmund
Edgar
Frank (Francis?)
Charles
Arthur
James
William
John
Robert
Thomas
Peter
Phillip
George

Oliver or Hugo

My immediate thought was either Thomas or William, but you might prefer something less popular. There are lots of great suggestions above.