Once you've started putting your main character to use in your marketing, social media, giveaways, events and merchandise, you might like to consider expanding your storytelling universe by creating more friends or family members, and a universe for them to exist in.
Disney started with Mickey well before anyone saw Minnie, Donald, Daisy, Goofy or Pluto. Similarly, LINE friends started with Moon before before they grew their cast of characters and Brown, Cony, James, Sally and Leonard came along (https://www.dalziel-pow.com/news/rise-line-friends-retail)
There are several advantages to expanding your character family:
Your main character can interact and speak with the other characters
You can tell more stories and explore a wider variety of situations
Broaden your appeal - different people will connect with different characters
Using our own brand mascot, Floob, we created "The Floobiverse", a cast of characters each with their own likes, dislikes, powers, personalities, goals, mottos and even secrets. This has drastically increased the interest we have been getting from the public, potential partners, licensees, and recently, NFT platforms.
We even created a fictitious land of paint called "Chromia" [from the Latin for "colour"], where Floob meets these new characters, forms different kind of relationships with each of them (even including one character, Squiddie, who becomes his nemesis) and goes on to have adventures with them.
This is world-building - creating entire environments with their own unique props, geography, weather, history and magical properties. According to Catreece MacLoed (Creator of Saorsa, World Designer; Game Designer, Writer), "Strong worldbuilding is probably the single greatest thing you can provide to an intellectual property to make it do well financially and to get the audience interested in what’s going on, as well as to maintain the product line".
Finally, a little sneak peak into what we are planning for The Floobiverse.. Rather than limiting it to just a land of paint, we're opening up the storytelling possibilities even more so that Chromia is in fact a metaverse, with each world representing a different artistic medium or technology. Floob's first contact is with the Land of Paint, but as he goes on his journey to get back to his artist father in our human reality, he goes through any number of portals that transport him to a variety of new worlds, each with their own look and feel: