Pinkie Pie loves her son very much, but unfortunately, he doesn’t feel the same.
Pinkie and Skystar had three children of their own through magic, and the process took a major toll on both of them. So, once their three hatchlings were school aged, Pinkie and Skystar decided that they had room in their home and hearts to foster and maybe adopt a few pony children in need. They first fostered Kiwi Kiss, who pretty quickly made it clear to her foster parents that she wanted to stay forever, and was adopted. After this resounding success, Pinkie and Skystar turned to the ponyville orphanage. There they found Strawberry Swirl, a 13 year old who had been removed from his home due to severe neglect. He was standoffish, nervous, and was considered a ‘special case’. Pinkie and Skystar thought that bringing the boy to Seaquestria for a new start would help him. It did not.
Strawberry was pretty instantly unhappy. While his home life was terrible, he had his friends. In Seaquestria he was alone, with his only company being his foster family and the nosy hippogriffs who lived in the kingdom. He was miserable. He began picking fights with his schoolmates, bullying his foster siblings, and intentionally hurting Pinkie and Skystar. The only pony Strawberry showed any kindness to was Saltwater Taffy, the youngest child Pinkie and Skystar adopted. Taffy was rescued from pony trafficking and was deeply scared by this, and Strawberry saw himself in her. The only time the young stallion was gentle and quiet was when he was with her. But unfortunately, his friendship with her could not change how he felt about the rest of his situation.
Strawberry began to sneak off whenever he could, walking to the nearby pony towns whenever he could. There, he made a few friends, but he also contacted vampirism after being mugged one night. After this, things got worse. Not only was Strawberry mean, but now he was violent on occasion. After a fight with a schoolmate ended up putting the other pony in the hospital, Strawberry ran away. He disappeared without much of a trace, only leaving a note to his foster family that he wasn’t going to bother them anymore. Pinkie and Skystar were devastated.
Strawberry vanished, running off into the Everfree to live amongst other ponies like him, where the Thrace ponies could live and feed without judgement. He writes home occasionally to Saltwater Taffy, and will sometimes tell her to tell Pinkie and Skystar that he’s doing ok, but other than that, nobody hears from Strawberry. Now that he is well fed and isn’t under constant supervision from the state and his family, he feels better, and has begun to heal. Part of him feels guilt for how he treated his foster family, he wishes sometimes he could go home to them, but he fears that they will send him away. He’s wrong, of course, but he doesn’t know that.
Pinkie on the other hand, misses her foster son terribly, and often dreams of what life could have been like if things were better. Some day, far in the future, when Strawberry is healthier and has healed more and reassessed how he behaved, and Pinkie apologizes for taking Strawberry away from his friends, the two of them will finally meet on the same level and learn to love each other as family, in their own broken and cobbled together way.