You can start by looking on popular fanfiction websites like Archive of Our Own (AO3). Just type in 'Morgan calls Reid baby boy' in the search bar, and it should show relevant stories. Fanfiction.net is another option, but AO3 usually has a wider range of stories with better tagging systems.
Try using Tumblr as well. There are often fanfiction writers who post snippets or links to their stories on Tumblr. Search for tags like 'Criminal Minds fanfiction', 'Morgan Reid', and 'Morgan calls Reid baby boy'. You might also find fan communities dedicated to Criminal Minds fanfiction where people can recommend stories with this specific element.
Another way is to join Criminal Minds fanfiction groups on Facebook or other social media platforms. Ask the members if they know of any fanfictions where Morgan calls Reid 'baby boy'. They might be able to point you to some great stories or even share their own unpublished works that have this theme.
Chapter 11, "She Smiled, He Panicked", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. It opens with After a meeting, Shang Shaojing pinched the bridge of his nose,...
Chapter 63, "Far Exceeded Expectations!", is the clearest early answer because it turns Xingmei Entertainment's situation into a concrete plot event. The chapter turns that into something concrete by moving from During those seven days, he thought he had completely escaped from...
Chapter 16, "He Actually Fell Asleep", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event. The chapter gives readers a real answer by opening on Just as the words fell, Jiang Shixu swiftly cast his eyes downward.
Chapter 139, "I Will Help You Chase Shang Shaojing!", is the clearest early answer because it turns Chase Shang Shaojing's situation into a concrete plot event. It opens with Wen Jiaojiao's live stream was inundated with a wave of question...
Chapter 281, "Zhao Lang, Are You Willing to Take a Gamble?", is the clearest early answer because it turns Take's situation into a concrete plot event. A useful checkpoint is the way the scene starts with In his dream, he found himself in a strange world.
Chapter 312, "Charity Gala Invitation", is the clearest early answer because it turns Du Sang's situation into a concrete plot event.
Chapter 249, "Maxing Out Wilderness Survival Skills!", is the clearest early answer because the violence around Aunt Liu becomes final instead of hypothetical.
Chapter 132, "Looking at me with that kind of eyes, are you afraid I'll eat you?", is the clearest early answer because it turns Zhao's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The new girl in the live-streaming room went crazy.
Chapter 66, "This Sister Really Can Hustle!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event.
Chapter 15, "The Autistic Teen Jiang Shixu", is the clearest early answer because it turns Jiang Shixu Jiang's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Shixu woke up from those nightmares filled with blood and...