Jo needs Ellen more than she lets on, and that's been an ongoing theme in their relationship for as long as she can remember.
It's different now.
Ellen isn't in Chicago. Ellen is living out a future Castiel finally admitted to, and it haunts her more than she'll say it. Before her father died, Christmas was something she looked forward to. They were a family, after all. Ellen would smile whenever Bill was around, and Jo was still in pigtails, naive enough to not know better, and her father was her hero.
But children grow up.
And Jo rarely lets herself get attached to anything because it is never for good.
Things and people are transitory. Things end and things begin and they end again.
You never get anything back once it's been lost.
At least, that's what she's always thought. Until she wakes up to find her knife collection in her room on Christmas morning. She thinks it has to be some kind of sick joke at first. But she checks, and double checks, and sure enough, they're hers. Jo knows how each and every one of those knives have been used.
Surprisingly enough, it's not the knives that make the gift. It's the postcards hidden underneath. Postcards she never received, because she found herself in Chicago instead of wherever she was supposed to go next. They read Joanna Beth.
She reads the postcards that weren't ever sent since Ellen didn't know where to send them to, a damn knot in her throat that she can't get rid of, and she sees it, now.
For so long she'd been hellbent on following her father's footsteps, she hadn't noticed she possessed her mother's walk.