Selden is a character who appears only briefly in the story, but he plays a significant role in the mystery. Watson encounters him while investigating the case in London, and Selden's presence on the TOR (Telegraphic Office Repeater) adds to the intrigue surrounding the Baskerville curse and the possibility of someone using the telegraph to communicate with the mysterious figure on the moors.
However, Selden's true identity and purpose remain unclear. He is never directly linked to the events on Dartmoor, and his role in the story remains ambiguous. Some readers believe he could be connected to the real killer or have information about the true nature of the curse.
The mystery surrounding Selden's identity adds to the suspense and ambiguity of "The Hound of the Baskervilles," leaving readers to speculate about his true intentions and role in the story.