I think a lot of the shyt about side pieces the way it is discussed is
On the Internet brehs make it sound like the girl is so in love w the dikk that she's on call even tho the breh never takes her on dates or claims her or any of that shyt
If we thinking reality side pieces is one of two things
1) a girl who convinced yall are dating or on the way to dating who you act w as if she was ya girl. If she know you have a main chick you gotta do constant damage control about how you like her more but you w ya girl for dah dah dah reason..
2) some booty call w low self esteem that you smash out irregularly, probably since before you started w ya chick. She probably doesn't hesitate to disrespect or ignore calls but every so often will break down and give up the smash
At least that's what I'm used to seeing. Brehs act like they be on that

mistress life but a mistress ain't a side chick in my opinion a mistress requires the existence of some sort of legitimate power dynamic
Edit: I forgot door three - ya side chick is ugly and ain't got options and knows it that's why she puts up w ya shyt