Alterous attraction is a form of tertiary attraction that is described as not being entirely platonic or romantic. It typically constitutes a level of emotional closeness usually more than what is considered normal for an entirely platonic relationship, but does not fall into what would be considered to be a romantic relationship.
Alterous attraction is very similar to queerplatonic attraction.
Flag
The alterous flag was made in 2016 by Tumblr user Alterous-Albatross. According to Alterous-Albatross "The yellow stands for platonic. The gray stands for the gray area between romantic and platonic attraction. Pink represents affection. Red represents romantic."[1] The red and yellow are muted to show that it is not entirely platonic or romantic.