She'll just watch unless he decides to invite her to help.
Elspeth conjures up a book and reads it with half an eye, the rest of her attention on Harley.
It's a short story collection. "Would you rather I read to you for a bit than keep working on your pond?" Elspeth asks.
"All right," she says, and she finds something loosely age-appropriate - though Elspeth is not nearly good enough at keeping secrets to sustain this perfectly, she can manage as a general rule - and puts her arm around Harley and reads it aloud.
Okay then. Cuddles. Elspeth starts looking for another story acceptable for a toddler.
They've been out long enough that he's getting a little pink. She conjures him a bottle of ice water and hands it over; he wanted to try sunburn, not sunstroke. Then she finds a story that she thinks will be okay and starts reading it.
This story too ends eventually.
Elspeth does wonder what will happen to a small Joker who is hugged whenever he likes. Perhaps it won't make much long-term difference. But short-term difference suffices.