A Little Bit of Sunshine
Lena Luthor has had a target on her back thanks to her family. The repeated attacks on her life have left her with PTSD and unbearable nightmares. Her only relief is when she can let herself be little in the complete privacy of her own home. That is until she meets a new mommy and comes to find out that this new mommy might actually be someone who knows them in real life.
or
Lena really needs a mommy but will she let Kara be that mommy for her or will she completely push her away like she does most things in life?
I suck at summaries. If you don't like Little/Caregiver fics, please find something else to read. All scenes in that headspace are non sexual.