Use sed to replace a part of a line with a variable

Question

So right now I have a variable

var1='batman'

I also have a file wrong.txt that reads as follows

John="Superman lives in Gotham City."
John="Superman's parents were killed in Crime Alley."
James="Superman does not have a bat-mobile."

Now I want to change the file's contents using sed. Obviously, I need to replace Superman with batman. I tried doing it with sed, but there were no changes made to the file.

Here is what I did

sed -i -e "s/John=\"Superman/John=\"$var1/g" wrong.txt

Answer 1

sed 's/^\(John="\)Superman/\1'"$var1/g" <in file

...ought to work.