That may be fine. That may even be part of their function in the story. But if the audience does need to remember them, then give them something unique.
Unique Gift
What can they do that nobody else can do? Again, this can be nothing. But if it is, the character will be more forgettable. Also, this doesn’t mean nobody else can do the thing in the whole world. But nobody can do the thing in the main cast or the core group.
Look at the X-Men, overlapping mutant powers are vanishingly rare. There are notable exceptions like X-23: Wolverine’s clone/daughter, who obviously shares most of his powers. But as a general rule, an X-Man’s powers are unique, and thus memorable.
But this doesn’t have to be so obvious. Maybe they have unique knowledge. Maybe they have a unique hobby or skill. Something to make them stand out. Maybe they can juggle? Maybe they can style hair? Maybe they can navigate by the stars? Maybe they can play chess?
