Day returned — again. Day is my daughter’s security blanket, a small square of blue felt with a satin border she likes to move her fingers along like a set of worry beads.

We are not positive how the blanket got its name, but we think it started when Pickle (her nickname) was a baby and her mother Cathlin would come home from work and ask, “How was your day?”

It is also possible that there is no connection between the phrase and the blanket’s name. We have had this blanket, off and on, since Pickle was born. She is now nine years old and just started fourth grade.

Day has had a boomerang life, periodically getting lost and then resurfacing sometimes as much as a year later. The most recent journey was beneath a bed at grandma’s house where it lay undisturbed for about five months, until a late summer cleaning spree unearthed it.

Because Pickle is older now, the absence of her blanket was not so acute, and she found a substitute rather quickly — a wooden stake whittled to a point by her older brother, a bottle of holy water and a cross. This summer we started watching Buffy the Vampire Slayer and Pickle fancies herself a slayer too. The other day she suggested we take a walk down Snake Hollow Road, across from the Tashmoo Overlook.

“I don’t trust that road,” she told me.

We went at dusk, parking at the overlook and then walking hand in hand down the dark and wooded road. In her other hand Pickle carried a green purse which held her stake, cross and holy water. The walk was uneventful, no vampires or even snakes, but we plan to go back soon.

My 13-year-old son Hardy had no interest in watching Buffy, so this summer I took him on a separate 1990s television journey: the original Twin Peaks. Recently, we watched the third episode, the one that includes a dream sequence with a dancing dwarf speaking a foreign language, possibly Eastern European or possibly made up.

The last time I saw that dancing dwarf was nearly 30 years ago, when I was in my 20s and living on 35th street and 9th avenue, in a New York city neighborhood so bad and abandoned it didn’t even have a scary name like its neighbor to the north, Hell’s Kitchen. A mysterious blow dart attacker roamed the neighborhood, and most nights I drank too much as I hid from the person I wanted to be.

While watching TV with Hardy I couldn’t help sneaking looks at him, marveling that the teenager sitting next to me was the same person I once held in my arms, rocking him to sleep in the delivery room on the day he was born. I also couldn’t help sneaking looks at me, and giving thanks for the confused clarity of fatherhood.

In preschool, Day disappeared for over a year, somewhere in Aquinnah. I can still remember when we lost her, retracing my steps many times and then standing at the top of the cliffs looking out to sea at my failure as a father and the impending doom of many sleepless nights.

During that absence, we developed a new bedtime ritual to take the place of snuggling with Day, a version of counting sheep but with a lot more variety. While I scratched her back I had to come up with a new animal for her to count each night. Repeats were allowed but only under a conditional basis, one that Pickle ruled over with an arbitrary hand. At some point in this process Pickle rolled over on her back and lifted her arm over her head, perhaps to stretch. Without hesitating I put my forehead in her armpit and she in turn did not hesitate either. She counted to five and then said, “okay, I’m ready for sleep.”

This was the sort of game-time audible call you never read about in any parenting book or magazine. But it worked and even now, so many years later, I am still putting my forehead in her armpit for five seconds every night.

A year after losing Day, while getting a fish taco at Faith’s Fish Shack on the Aquinnah Cliffs, I saw the blue blanket sitting on the counter, hanging out as if part of the food crew. I whooped and clapped and cried I was so happy to see it. But when I presented the blanket to Pickle at the end of her school day, she just shrugged as if the absence had been merely a matter of hours.

A few years later, second grade I think, I told Pickle she was the perfect age and that I would prefer it if she stopped getting older. It was just an offhand comment I thought, a bit of a joke although wrapped up in the real feelings of a dad who deep down does not want his daughter to grow up.

Later that same day I heard Pickle talking to Cathlin and crying. “Dad doesn’t want me to get older but I can’t help it,” she sobbed. Since that day I have not said out loud to either of my children that I want them to stop growing up. But each day I think about it.

On the first day of fourth grade, Pickle happily accepted my hand as we walked into school. Hardy had pulled his hand away at the start of third grade and so I wasn’t sure what to expect.

In the classroom, her teacher showed us a jar with a chrysalis hanging from the top. It will be a monarch butterfly in a few days, she explained. The next day there was another jar with three caterpillars crawling about on some twigs and munching on leaves. A few days later they too morphed into chrysalises.

I quickly became obsessed with these small green orbs, hanging from the tops of their jars. They seemed so fragile, holding on by just a wisp, but also quietly powerful, doing nothing to the naked eye, but behind the scenes changing completely. Each morning at drop-off, I stared at them intently while Pickle and her friends milled about the classroom.

It took about a week for the butterflies to emerge. I was not there when it happened but Pickle told me about it in great detail, how the butterflies appeared seemingly out of nowhere, fully grown and with beautiful wings. The class all went outside to set them free.

That was where Pickle’s retelling of the moment ended. But in my mind’s eye I continued to watch the butterflies soar above the playground, neither lingering nor looking back. Instead, they just lifted off into the air, proud of their new wings and bodies as they disappeared forever into the trees.

I wished them safe travels, clear of hungry predators — from birds to vampires to the passage of time.