The relationship between Pack Mom and Isaac could develop through acts of care. For example, Pack Mom cooks for Isaac, helps him with his homework if he's still in school in the fic. This makes Isaac trust her more. Stiles and Isaac's relationship might start with Stiles being a bit wary of Isaac as a new addition to the pack. But as they go on adventures together, like facing a minor werewolf problem in the neighborhood, they become closer friends. And as for Pack Mom and Stiles, they could have a deeper bond as they both care for Isaac.
One idea could be that Pack Mom takes in Isaac when he's injured. She nurses him back to health and in the process, Isaac starts to see her as a mother figure. Stiles is initially jealous but then realizes how much Isaac needs that maternal love. Another plot could involve a threat to the pack where Pack Mom, Stiles and Isaac have to work together to protect the others. Isaac discovers a new power during this time which helps them in the fight.
You can try fanfiction websites like Archive of Our Own (AO3). Just go to the site and use the search bar to type in 'Pack Mom Stiles baby Liam'. There might be some great stories there.
One common theme is protection. Stiles often takes on the role of protecting Baby Liam, just like a mother figure would. It shows their bond in a very endearing way.
The pack mom's relationship with Baby Jackson could be one of nurturing and protection. She could sing lullabies to him that have a hidden supernatural meaning, which only Jackson can sense. As Jackson grows, he starts to see the pack mom as his main source of comfort. And this relationship could also influence how the pack as a whole views Jackson. If the pack mom shows strong affection for him, it could make the other pack members more accepting of the baby, who might be different from them in many ways.
A possible plot could involve the pack mom trying to raise Baby Jackson while Stiles acts as an unexpected mentor. Stiles, with his quick thinking and knowledge of the supernatural, helps the baby develop in a way that surprises everyone in the pack. For example, he might teach Jackson how to control his emerging powers at a very young age. This could lead to a series of adventures where they all have to face different challenges together, like fending off other supernatural beings who are jealous of Jackson's potential.
It's popular because it gives a new and interesting dynamic to the character of Stiles. Instead of just being the sidekick, he becomes a central figure of care and support in the pack.
You can try Archive of Our Own (AO3). It has a vast collection of fanfictions including ones about Isaac and Stiles having a baby. Just use the search bar and type in relevant keywords like 'Isaac Stiles baby' and you'll likely find a lot of stories.
One great story could be 'The Unlikely Bond'. It focuses on how Isaac and Stiles navigate the new situation of having a baby. It shows their growth as characters and how they deal with the challenges of parenthood. The story is full of heartwarming moments and also some tense ones as they face society's reactions.
One great story could be 'The Pack Mom's Guidance'. In this fanfiction, Stiles takes on the role of pack mom in a really heartwarming way. He looks after the pack members, making sure they are safe and happy. Another good one might be 'Stiles: The True Pack Mom' where he uses his intelligence to solve pack problems like a mother would for her family.