A [trope] common in fiction and fanfiction. It is the phenomenon where a group of people come to love each other like family, even through (and because) they aren't biologically related. The LGBTQ+ community in particular tends to favor this trope because it allows them to escape [overbearing] or harmful biological family.
Found families can be found in [real-life] as well, as close friend groups may feel closer to each other than to biological family.
Found Family is also known as Families of Choice.