How would you make betas interesting and not just background characters?

I was browsing Tumblr and came across this post and really loved the idea of a beta being able to go through a rut, and a heat, depending on their chosen partner. https://www.tumblr.com/abo-dreams/168271972193/betasverse-betas-can-go-into-heats-and-ruts-but

What are betas in your personal opinion and how would you make them interesting? Everyone seems to have a different version of them.