Harry Potter and the Sorcerers Stone could have featured a brand new character created exclusively for the movies, and this tiny addition would have made Harry's years with the Dursleys even more upsetting.
Steve Kloves, who was responsible for screenwriting every Harry Potter movie bar, had his own ideas for a small yet immensely poignant character who never made it to screen, and this interview with i09 I've recently dug out of the archives gives us all the details.
So, who was this potential new soul in the Potterverse? Klove's idea for a character was tiny spider named Alastair who a young Potter befriended in order to deal with the isolation of his years under the stairs. When asked if he created his own characters, Kloves told interviewers that:
Yes, I did. I did. Alastair. It was a spider in the closet, in the cupbord in the beginning, who he [Harry Potter] had befriended and talked to. My vision of the first movie was quite different in terms of how you first perceived him [Harry]. There was a spider in there and all these broken soldiers that he had filched from the rubbish bin of Dudley's [bedroom]. And he had this broken army and he would talk to Alastair.
These tragic beginnings would have led to a very different escape to Hogwarts that was designed to make viewers question Harry's sanity, Klove explained that:
When Hagrid arrived in the motorcycle you wondered if maybe Harry was mad, and was imagining being rescued. Then you found out it was real. That was my original vision of the movie
While this might all sound totally bizarre to us now that we know the Potter movies so well, Kloves' adaptation of the novels has been almost universally praised and I have high hopes that this could have been an excellent way to highlight Harry's unfathomable loneliness before his wizarding years.
Can you imagine the pathos of a scene where Dudley swatted Harry's only friend with a newspaper? It's making me tear up just thinking about it...