Word for a person being used

I'm looking for a word to describe someone who is being used. I want a noun to describe this person, not a verb or or adjective. Maybe like a pushover.

A pawn can be somebody who's being pushed around, or used for somebody else's benefit, often without being aware of it:

• a person, group, etc, manipulated by another

Patsy. Although this is specific to accountability being transferred unfairly, as in someone taking the blame for someone else's crime.

Sucker. This is pretty good for many cases.

Neither apply to a romantic relationship, though. If that's what you're looking for.

Perhaps doormat, as in "(s)he's walking all over you".