This guy's very name epitomizes loneliness. That's pretty clear, right? His character ties into the rest of the book because the gestalt, the novel's subject, grows around him as the solution to what the novel sees as a chief problem in life: loneliness.
That's why tracking his evolution in the book spells out the first steps of the gestalt's evolution. After all, he's its first head.
Lone starts at age twenty-five, but mentally, he's a feeble-minded child. He's as alone as can be, even while around others:
Men turned away from him, women would not look, children stopped and watched him. He expected nothing from any of them…[he] heard the sounds [of their speech] but they had no meaning for him. He lived inside somewhere, apart. (1.1.2)
He's got a trick up his sleeve, however; he just doesn't know it yet. It's that recorder-like thing inside him. It's an "alive and independent core" whereas the rest of him is a "half-dead animal" (1.3.2). Yeah, that dealio is a little confusing. Basically, this passive instrument in him simply receives signals from the newborn—until he hears the call from Evelyn.
That's when his life starts to change. The recorder, more or less, is responsible for him understanding the call well enough to go find Evelyn. He and she merge emotionally, barely even touching:
Their silent radiations reached out to each other, mixed and mingled and meshed. Silently they lived in each other. (1.7.3)
This merging becomes his "bench-mark" in life (1.29.17). Notice that this magical bonding is similar to the mind-powers in the book. They are merging, just like thoughts in telepathy merge or the individuals of the gestalt merge.
It's fair to say his time with Evelyn puts him in a position where the other lonely members of the gestalt—starting with Janie and the twins—join him in his shelter. That merging with Evelyn, though, led to the attack on him by her father, Mr. Kew. Lone is badly wounded and the Prodd family takes him in.
The Prodds heal and nurture him. Under their care, he learns to talk, which evolves him further so that more of his personality develops.
But his personality remains a simple one. "It took him five years to learn to talk and always he preferred not to" (1.11.16). He's physically strong, able to fell trees with an ax to improve the shelter. He takes a simple name: "Lone," meaning, "All alone" (1.11.9-10). Um, emo much?
When it comes to Lone, there's a lot more than initially meets the eye. The dude's got compassion. He remembers Mrs. Prodd feeding him, and that leads him to feed Janie and the twins. Once Gerry reaches the shelter, Lone feeds him too. He never says it explicitly, but it's clear he wants the kids to feel the same sense of belonging he felt with Evelyn. That's the cure for the loneliness they share.
His life with the Prodds teaches him an insufficient type of belonging. He realizes they were ready to boot him out at any time, because really he was just a replacement for the child they couldn't have. He wasn't loved for who he was. As the novel puts it in Lone's thoughts:
Prodd and his wife had shucked him off when he was in the way, after all those years, and that meant they were ready to do it the first year and the second and the fifth—all the time, any time. You can't say you're a part of anything, anybody, that feels free to do that to you. But friends . . . maybe they just don't like him for a while, maybe they loved him all the way through. (1.29.14)
It's no coincidence that after the Prodds help him advance, Lone brings Baby from their farm to the gestalt. It's not because he's bitter about being a replacement child for the Prodds. It's because he's growing as an individual, and since he is also the gestalt, that means the unique life form gains more parts. And besides, Mr. Prodd isn't able to care for Baby.
Despite all his growth, the gestalt remains fundamentally roadblocked so long as he's the head. At the end of Part 1, Lone finally feels free of his loneliness:
I belong. Part of you, part of you and you too [...] Lone thought his heart was going to burst. (1.29.35-37).
He is thrilled by the possibilities:
He looked at them, all, every one: arms to flex and reach, a body to care and repair, a brainless but faultless computer and—the head to direct it. (1.29.37)
Exuberant, he says:
And we'll grow, Baby. We just got born! (1.29.38).
Alas, further growth is not to be. Baby says they're not likely to do anything, because the gestalt is an "idiot," a fabulous, bumbling idiot. (1.29.39).
That's because he, Lone, is its head. "So it was that Lone came to know himself," the novel comments. Not many are able to do that, Part 1 concludes, but "he found, at this pinnacle, the rugged foot of a mountain" (1.29.40).
So after all that loneliness, he's just stuck? Not quite.
Lone does the best he can to advance the gestalt. He brings Gerry in once he and the kids realize Gerry's crucial for their future. Lone tracks down turpentine and other materials the gestalt needs to prepare for when it can grow someday in the future. (Janie uses the turpentine to paint pictures that apparently help the gestalt gain knowledge.)
Lone finds Alicia Kew and orders her to help him figure out what exactly he is. "I got to know about that," he says when she brings up the concept of the gestalt. "There is such a thing. I want to know if it ever happened before" (2.11.47). He later adds, "I want a book about that kind of animal that is me when I'm finished [with growing]" (2.11.57). He searches hard for an answer that will help the rest of his life form.
He concludes of his gestalt:
But maybe the right kind of head'll come along after I'm all organized. Then it'll be something. (2.11.62)
Then he gets hit by a tree and dies. Yeah, pretty anti-climactic, we know. But then again, so is he as the head of the gestalt. So we guess it's a fitting end. At least he remained compassionate, telling the kids to go to Miss Alicia Kew for security should something happen to him.
Like Gerry, the second head of the gestalt, Lone has the ability to read minds, to probe them and gain their knowledge. He can also use his power to make people do or forget things. He uses it to make Mr. Kew kill himself. When he exercises this power, his eyes spin like wheels.