This is a pretty cool topic! I've never actually thought about this with my RP characters.
I usually play the too nice/feels bad for everything she does type characters, it's always been hard for me to RP as a aggressive character.
I've had one Doormat related character and she kept to herself a lot, didn't like being 'the center of attention', but she cared deeply for her comerads , she just didn't like showing that affection.
Her backstory wasn't good either, which back fired on her. She consently pushed away people who tried to get to know her.
That was probably my most favortie character to RP as and I still do!