The only thing more difficult than conventional family dynamics are those in families that are the product of a second marriage. Sibling rivalries are only heightened when they're not your 'real' brother or sister. As a kid, it's easy to become insecure that a newfound dynamic at home might leave you feeling like an afterthought.
Acting out is to be expected in these kinds of situations, but it's not always the case that a child will go as far as one Redditor's teenage daughter. Posting on AITA, the mom queried whether she was in the wrong for disciplining her after a momentous event. After the sixteen year old fought with her nearly fifteen year old stepsister, she ruined her $3000 quinceañera dress with tears and marker pen.
Protesting when told she would have to pay back the cost by getting a job, Redditors were astounded that the mom worried she was doing the wrong thing. It was some truly spiteful behavior.