Williott means Will + Elliott. Will and Elliott is a very popular pairing, and a lot of Tunnels fans believe they will be a pair. Here is a summary of how their relationship has changed through the books.
Elliott makes her first appearance in this book. She and Drake find Will and Chester; they save them from the Styx. They take care of them, and they also save Will's brother, Cal, from the sugar trap. One night, Elliott invites Will to come with her, on her guard circular. Suddenly a pair of Limiters walk by, and Will and Elliott hide, so the Limiters don't see them. When they walked away, Will gets into an outbreak with Elliott and blames her for being unattentive. She gets angry at him, and doesn't talk to him anymore. Elliott begins to hang out more with Chester, and ignores Will, but still respects him for his bravery. In the end of Deeper, she tethers herself to the rest of the group to get down into the Pore. During the Styx fight at the Pore, she and Will end up falling into it.
They survive the fall, and wake up on one of the Pore's fungal outgrowths. Will and Chester find Elliott unconscious, with her arm broken. They take her with them, and they meet Martha, who takes them to her shack. But Elliott gets worse, since she has now got some kind of fever. But they find medicine, and this saves her. Then, Will finds his dad Dr. Burrows. But Dr. Burrows jumps down into another void called Smoking Jean and Will follows. So does Elliott, although Will doesn't know. They find the Garden Of The Second Sun and discover the Rebeccas' cave lair. Elliott wants Will to just sit down, and let her do the job. But he feels he has got to do something for her. He tries to sneak in to steal the Dominion phials, but is caught and a fight ensues. Elliott's charges go off, destroying the cave, but Will still manages to get the phials. Outsides, she kisses him on the cheek.
Will and Elliott get really close as friends in the inner world. Will would like to tell Elliott about his romantic feelings for her-but he is unable. Then Will and his dad get taken as hostages, by the Rebeccas. They want the Dominion phials back, which Elliott has. She tries to save them, but comes to the pyramid too late. They have already killed Dr. Burrows, and Will is terrified. Elliott gives Styx the virus, but before coming to the pyramid she swallows the vaccine. Will is not aware of that, and gets really angry at her. They argue while Colonel Bismarck evacuates them from the Styx with New German helicopter. Will then tells Elliott that Drake would be ashamed of her, and that she is not worth being his companion. And she tells him he is overreacting, and that it wasn't her who killed his father. They both claim they will never be a pair again. When the arguing is over, Elliott reveals to Will that she swallowed the Dominion vaccine. They then apologize each other, then climb back to Topsoil. When they're almost there, Will begins to cry, because he remembers his dead father. He is embarresed, but Elliott tells him not to be, and hugs him tight. She is just about to kiss him, when he walks away again, unaware of what she intended to do. They finally reach Topsoil, and end up staying at a secret manor owned by Drake's dad Parry. There, Elliott gets really different - she acts really girly, wears makeup, dresses and becomes even more attractive.
Elliott is still girly in the beginning, but she then cuts her hair off again, and stops using makeup. Elliott's dad, Eddie, tells them that she may be ready for The Phase soon, and may be highly dangerous. But the medical examination results show that she's too young for the Phase. When she comes out from the medical examination, she meets Will who has been waiting for her. She runs into his arms and hugs him tight. She also kisses him on the cheek, and smiles. In the end of Spiral, Will and Elliott are again stuck in the Garden Of The Second Sun, and sit on the top of the pyramid. Elliott tells him that she is in love with him, and they hug.
Elliott and Will are the last living people in the Garden Of The Second Sun, and in the first episode they are scavenging for suplies in the abandoned New German gigantic mall. There Will asks Elliott if she wants a new dress and Elliott denies. When they start heading home Elliot mentions several times that Will is getting "old", meaning that he wants to live with less adventures and more peacefully. They then find a sweet's store which looks suspiously clean, like being used recently. Then they find two New Germanians, a child Karl, and his father, Jurgen in hazmat suits. When they find out that Will and Elliott have a vaccine in their blood he asks them to accompany him to the science lab, where his brother, Werner could extract the vaccine. Inside the medical station Will tells Elliott to not look at each other while they change their clothes and eventually get naked, but after they do that, Elliott tells Will that he is "quite muscular" revealing, that she was peeking on him after all. Will responds, that her dimples are beautiful. Elliott becomes thrilled and asks Will something, but their flirting is interupted by Werner and Jurgen, who are ready to begin the extraction of the vaccine. Later, when a survived bushman starts acting strangely and says something to Elliott in Styx language, they head out to the pyramids, where Elliott makes the pyramids fly away with a strange device, making a giant tower of some unindentified glowing material appear from the ground. Inside the tower she toggles a strange system, that is able to show a live sight of the planet Earth. She then behaves strangely for several days and then tells Will, that something is terribly wrong with the tower, that something is missing. Then she teleports Will and herself to London, where they go to the British Museum.
There Elliott removes the top part of a Sarcophagus and takes out a scepter. Later, the Styx capture Will, and Elliott is forced to watch how Alex injects her larvae into Will's inside. When she finds out that the USA's submarine has initiated the nuclear strike sequence because of the international threat - Armagi. She activates the scepter while fighting with Alex. Her last words to Will were that she has to go, and that he doesn't need her "like that" meaning her new insect legs. She then teleports all the Styx back to the Garden Of The Second Sun revealing that all the Styx are aliens and destroying all of the Armagi. She then barricade's inside the tower and "sets course back" meaning probably the home system or planet, from where the Styx are originally from. In the end, Will is in the Colony when he scares a new Bartleby, and hears his mother say that she's smelling a Styx inside a house. Will then thinks about all the strange things, that been happening to him lately (enjoying being in the dark, etc.) and starts wondering, if the ferments from the Styx larva's could've made him a different creature, a Styx (like Elliott).