Warning: Story spoilers and mentions of abuse. This version pretty much defies the canon version since Cosmo's father is involved and his mother is...a sadist...on her good days lol.
So for a while, after his siblings had been thrown out, Cosmo did as much as he could to please Nora. Yes, she was violent and cruel, but at least he wasn't out in the rain, and wasn't starving (as long as Linnie was around). Cosmo felt himself quite lucky that despite the violence, he at least had a roof over his head.
Only problem was his grades...Nora would constantly beat him since he hardly ever made As in school, and often reminded him of how much of a disappointment he was to her. It wasn't until he turned 12,000 that Nora has snapped, and decides to leave...leaving Linnie alone with Cosmo.
Linnie did the best he could with Cosmo. He replaced some of the toys and blankets that Nora had thrown away, made sure Cosmo had 3 warm meals a day, and taught him more personal things, like how pregnancy worked and using pads/tampons. He was also more patient with Cosmo's school work and often spoke warmly towards him.