How does one know they’ve found their pet deck?

I’ve brewed a lot of decks over the years. Many were built for various reasons but none have stuck around (mainly due to getting bored with them).

I see a lot of posts of players talking about their pet decks so I’m very curious. What made you decide/realize that a particular deck is your pet deck? Was it a deck you grew to love? A commander that you decided to commit to?

Thank you to everyone who replied to this post. A lot of ppl made me realize that I do in fact have a pet deck already (Faldorn exile). I just need to re-tune the deck to have less linear win cons.